diff options
Diffstat (limited to 'sys/kern/subr_mbuf.c')
| -rw-r--r-- | sys/kern/subr_mbuf.c | 1111 |
1 files changed, 1111 insertions, 0 deletions
diff --git a/sys/kern/subr_mbuf.c b/sys/kern/subr_mbuf.c new file mode 100644 index 0000000..74e1f56 --- /dev/null +++ b/sys/kern/subr_mbuf.c @@ -0,0 +1,1111 @@ +/*- + * Copyright (c) 2001 + * Bosko Milekic <bmilekic@FreeBSD.org>. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include "opt_param.h" +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/malloc.h> +#include <sys/mbuf.h> +#include <sys/lock.h> +#include <sys/mutex.h> +#include <sys/condvar.h> +#include <sys/smp.h> +#include <sys/kernel.h> +#include <sys/sysctl.h> +#include <sys/domain.h> +#include <sys/protosw.h> + +#include <vm/vm.h> +#include <vm/vm_kern.h> +#include <vm/vm_extern.h> +#include <vm/pmap.h> +#include <vm/vm_map.h> + +/* + * Maximum number of PCPU containers. If you know what you're doing you could + * explicitly define MBALLOC_NCPU to be exactly the number of CPUs on your + * system during compilation, and thus prevent kernel structure bloat. + * + * SMP and non-SMP kernels clearly have a different number of possible CPUs, + * but because we cannot assume a dense array of CPUs, we always allocate + * and traverse PCPU containers up to NCPU amount and merely check for + * CPU availability. + */ +#ifdef MBALLOC_NCPU +#define NCPU MBALLOC_NCPU +#else +#define NCPU MAXCPU +#endif + +/*- + * The mbuf allocator is heavily based on Alfred Perlstein's + * (alfred@FreeBSD.org) "memcache" allocator which is itself based + * on concepts from several per-CPU memory allocators. The difference + * between this allocator and memcache is that, among other things: + * + * (i) We don't free back to the map from the free() routine - we leave the + * option of implementing lazy freeing (from a kproc) in the future. + * + * (ii) We allocate from separate sub-maps of kmem_map, thus limiting the + * maximum number of allocatable objects of a given type. Further, + * we handle blocking on a cv in the case that the map is starved and + * we have to rely solely on cached (circulating) objects. + * + * The mbuf allocator keeps all objects that it allocates in mb_buckets. + * The buckets keep a page worth of objects (an object can be an mbuf or an + * mbuf cluster) and facilitate moving larger sets of contiguous objects + * from the per-CPU lists to the main list for the given object. The buckets + * also have an added advantage in that after several moves from a per-CPU + * list to the main list and back to the per-CPU list, contiguous objects + * are kept together, thus trying to put the TLB cache to good use. + * + * The buckets are kept on singly-linked lists called "containers." A container + * is protected by a mutex lock in order to ensure consistency. The mutex lock + * itself is allocated separately and attached to the container at boot time, + * thus allowing for certain containers to share the same mutex lock. Per-CPU + * containers for mbufs and mbuf clusters all share the same per-CPU + * lock whereas the "general system" containers (i.e., the "main lists") for + * these objects share one global lock. + */ +struct mb_bucket { + SLIST_ENTRY(mb_bucket) mb_blist; + int mb_owner; + int mb_numfree; + void *mb_free[0]; +}; + +struct mb_container { + SLIST_HEAD(mc_buckethd, mb_bucket) mc_bhead; + struct mtx *mc_lock; + int mc_numowner; + u_int mc_starved; + long *mc_types; + u_long *mc_objcount; + u_long *mc_numpgs; +}; + +struct mb_gen_list { + struct mb_container mb_cont; + struct cv mgl_mstarved; +}; + +struct mb_pcpu_list { + struct mb_container mb_cont; +}; + +/* + * Boot-time configurable object counts that will determine the maximum + * number of permitted objects in the mbuf and mcluster cases. In the + * ext counter (nmbcnt) case, it's just an indicator serving to scale + * kmem_map size properly - in other words, we may be allowed to allocate + * more than nmbcnt counters, whereas we will never be allowed to allocate + * more than nmbufs mbufs or nmbclusters mclusters. + * As for nsfbufs, it is used to indicate how many sendfile(2) buffers will be + * allocatable by the sfbuf allocator (found in uipc_syscalls.c) + */ +#ifndef NMBCLUSTERS +#define NMBCLUSTERS (1024 + maxusers * 64) +#endif +#ifndef NMBUFS +#define NMBUFS (nmbclusters * 2) +#endif +#ifndef NSFBUFS +#define NSFBUFS (512 + maxusers * 16) +#endif +#ifndef NMBCNTS +#define NMBCNTS (nmbclusters + nsfbufs) +#endif +int nmbufs; +int nmbclusters; +int nmbcnt; +int nsfbufs; + +/* + * Perform sanity checks of tunables declared above. + */ +static void +tunable_mbinit(void *dummy) +{ + + /* + * This has to be done before VM init. + */ + nmbclusters = NMBCLUSTERS; + TUNABLE_INT_FETCH("kern.ipc.nmbclusters", &nmbclusters); + nmbufs = NMBUFS; + TUNABLE_INT_FETCH("kern.ipc.nmbufs", &nmbufs); + nsfbufs = NSFBUFS; + TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs); + nmbcnt = NMBCNTS; + TUNABLE_INT_FETCH("kern.ipc.nmbcnt", &nmbcnt); + /* Sanity checks */ + if (nmbufs < nmbclusters * 2) + nmbufs = nmbclusters * 2; + if (nmbcnt < nmbclusters + nsfbufs) + nmbcnt = nmbclusters + nsfbufs; +} +SYSINIT(tunable_mbinit, SI_SUB_TUNABLES, SI_ORDER_ANY, tunable_mbinit, NULL); + +/* + * The freelist structures and mutex locks. The number statically declared + * here depends on the number of CPUs. + * + * We set up in such a way that all the objects (mbufs, clusters) + * share the same mutex lock. It has been established that we do not benefit + * from different locks for different objects, so we use the same lock, + * regardless of object type. + */ +struct mb_lstmngr { + struct mb_gen_list *ml_genlist; + struct mb_pcpu_list *ml_cntlst[NCPU]; + struct mb_bucket **ml_btable; + vm_map_t ml_map; + vm_offset_t ml_mapbase; + vm_offset_t ml_maptop; + int ml_mapfull; + u_int ml_objsize; + u_int *ml_wmhigh; +}; +static struct mb_lstmngr mb_list_mbuf, mb_list_clust; +static struct mtx mbuf_gen, mbuf_pcpu[NCPU]; + +/* + * Local macros for internal allocator structure manipulations. + */ +#ifdef SMP +#define MB_GET_PCPU_LIST(mb_lst) (mb_lst)->ml_cntlst[PCPU_GET(cpuid)] +#else +#define MB_GET_PCPU_LIST(mb_lst) (mb_lst)->ml_cntlst[0] +#endif + +#define MB_GET_GEN_LIST(mb_lst) (mb_lst)->ml_genlist + +#define MB_LOCK_CONT(mb_cnt) mtx_lock((mb_cnt)->mb_cont.mc_lock) + +#define MB_UNLOCK_CONT(mb_cnt) mtx_unlock((mb_cnt)->mb_cont.mc_lock) + +#define MB_GET_PCPU_LIST_NUM(mb_lst, num) \ + (mb_lst)->ml_cntlst[(num)] + +#define MB_BUCKET_INDX(mb_obj, mb_lst) \ + (int)(((caddr_t)(mb_obj) - (caddr_t)(mb_lst)->ml_mapbase) / PAGE_SIZE) + +#define MB_GET_OBJECT(mb_objp, mb_bckt, mb_lst) \ +{ \ + struct mc_buckethd *_mchd = &((mb_lst)->mb_cont.mc_bhead); \ + \ + (mb_bckt)->mb_numfree--; \ + (mb_objp) = (mb_bckt)->mb_free[((mb_bckt)->mb_numfree)]; \ + (*((mb_lst)->mb_cont.mc_objcount))--; \ + if ((mb_bckt)->mb_numfree == 0) { \ + SLIST_REMOVE_HEAD(_mchd, mb_blist); \ + SLIST_NEXT((mb_bckt), mb_blist) = NULL; \ + (mb_bckt)->mb_owner |= MB_BUCKET_FREE; \ + } \ +} + +#define MB_PUT_OBJECT(mb_objp, mb_bckt, mb_lst) \ + (mb_bckt)->mb_free[((mb_bckt)->mb_numfree)] = (mb_objp); \ + (mb_bckt)->mb_numfree++; \ + (*((mb_lst)->mb_cont.mc_objcount))++; + +#define MB_MBTYPES_INC(mb_cnt, mb_type, mb_num) \ + if ((mb_type) != MT_NOTMBUF) \ + (*((mb_cnt)->mb_cont.mc_types + (mb_type))) += (mb_num) + +#define MB_MBTYPES_DEC(mb_cnt, mb_type, mb_num) \ + if ((mb_type) != MT_NOTMBUF) \ + (*((mb_cnt)->mb_cont.mc_types + (mb_type))) -= (mb_num) + +/* + * Ownership of buckets/containers is represented by integers. The PCPU + * lists range from 0 to NCPU-1. We need a free numerical id for the general + * list (we use NCPU). We also need a non-conflicting free bit to indicate + * that the bucket is free and removed from a container, while not losing + * the bucket's originating container id. We use the highest bit + * for the free marker. + */ +#define MB_GENLIST_OWNER (NCPU) +#define MB_BUCKET_FREE (1 << (sizeof(int) * 8 - 1)) + +/* Statistics structures for allocator (per-CPU and general). */ +static struct mbpstat mb_statpcpu[NCPU + 1]; +struct mbstat mbstat; + +/* Sleep time for wait code (in ticks). */ +static int mbuf_wait = 64; + +static u_int mbuf_limit = 512; /* Upper limit on # of mbufs per CPU. */ +static u_int clust_limit = 128; /* Upper limit on # of clusters per CPU. */ + +/* + * Objects exported by sysctl(8). + */ +SYSCTL_DECL(_kern_ipc); +SYSCTL_INT(_kern_ipc, OID_AUTO, nmbclusters, CTLFLAG_RD, &nmbclusters, 0, + "Maximum number of mbuf clusters available"); +SYSCTL_INT(_kern_ipc, OID_AUTO, nmbufs, CTLFLAG_RD, &nmbufs, 0, + "Maximum number of mbufs available"); +SYSCTL_INT(_kern_ipc, OID_AUTO, nmbcnt, CTLFLAG_RD, &nmbcnt, 0, + "Number used to scale kmem_map to ensure sufficient space for counters"); +SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufs, CTLFLAG_RD, &nsfbufs, 0, + "Maximum number of sendfile(2) sf_bufs available"); +SYSCTL_INT(_kern_ipc, OID_AUTO, mbuf_wait, CTLFLAG_RW, &mbuf_wait, 0, + "Sleep time of mbuf subsystem wait allocations during exhaustion"); +SYSCTL_UINT(_kern_ipc, OID_AUTO, mbuf_limit, CTLFLAG_RW, &mbuf_limit, 0, + "Upper limit of number of mbufs allowed on each PCPU list"); +SYSCTL_UINT(_kern_ipc, OID_AUTO, clust_limit, CTLFLAG_RW, &clust_limit, 0, + "Upper limit of number of mbuf clusters allowed on each PCPU list"); +SYSCTL_STRUCT(_kern_ipc, OID_AUTO, mbstat, CTLFLAG_RD, &mbstat, mbstat, + "Mbuf general information and statistics"); +SYSCTL_OPAQUE(_kern_ipc, OID_AUTO, mb_statpcpu, CTLFLAG_RD, mb_statpcpu, + sizeof(mb_statpcpu), "S,", "Mbuf allocator per CPU statistics"); + +/* + * Prototypes of local allocator routines. + */ +static void *mb_alloc_wait(struct mb_lstmngr *, short); +static struct mb_bucket *mb_pop_cont(struct mb_lstmngr *, int, + struct mb_pcpu_list *); +static void mb_reclaim(void); +static void mbuf_init(void *); + +/* + * Initial allocation numbers. Each parameter represents the number of buckets + * of each object that will be placed initially in each PCPU container for + * said object. + */ +#define NMB_MBUF_INIT 4 +#define NMB_CLUST_INIT 16 + +/* + * Initialize the mbuf subsystem. + * + * We sub-divide the kmem_map into several submaps; this way, we don't have + * to worry about artificially limiting the number of mbuf or mbuf cluster + * allocations, due to fear of one type of allocation "stealing" address + * space initially reserved for another. + * + * Set up both the general containers and all the PCPU containers. Populate + * the PCPU containers with initial numbers. + */ +MALLOC_DEFINE(M_MBUF, "mbufmgr", "mbuf subsystem management structures"); +SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbuf_init, NULL) +void +mbuf_init(void *dummy) +{ + struct mb_pcpu_list *pcpu_cnt; + vm_size_t mb_map_size; + int i, j; + + /* + * Set up all the submaps, for each type of object that we deal + * with in this allocator. + */ + mb_map_size = (vm_size_t)(nmbufs * MSIZE); + mb_map_size = rounddown(mb_map_size, PAGE_SIZE); + mb_list_mbuf.ml_btable = malloc((unsigned long)mb_map_size / PAGE_SIZE * + sizeof(struct mb_bucket *), M_MBUF, M_NOWAIT); + if (mb_list_mbuf.ml_btable == NULL) + goto bad; + mb_list_mbuf.ml_map = kmem_suballoc(kmem_map,&(mb_list_mbuf.ml_mapbase), + &(mb_list_mbuf.ml_maptop), mb_map_size); + mb_list_mbuf.ml_map->system_map = 1; + mb_list_mbuf.ml_mapfull = 0; + mb_list_mbuf.ml_objsize = MSIZE; + mb_list_mbuf.ml_wmhigh = &mbuf_limit; + + mb_map_size = (vm_size_t)(nmbclusters * MCLBYTES); + mb_map_size = rounddown(mb_map_size, PAGE_SIZE); + mb_list_clust.ml_btable = malloc((unsigned long)mb_map_size / PAGE_SIZE + * sizeof(struct mb_bucket *), M_MBUF, M_NOWAIT); + if (mb_list_clust.ml_btable == NULL) + goto bad; + mb_list_clust.ml_map = kmem_suballoc(kmem_map, + &(mb_list_clust.ml_mapbase), &(mb_list_clust.ml_maptop), + mb_map_size); + mb_list_clust.ml_map->system_map = 1; + mb_list_clust.ml_mapfull = 0; + mb_list_clust.ml_objsize = MCLBYTES; + mb_list_clust.ml_wmhigh = &clust_limit; + + /* + * Allocate required general (global) containers for each object type. + */ + mb_list_mbuf.ml_genlist = malloc(sizeof(struct mb_gen_list), M_MBUF, + M_NOWAIT); + mb_list_clust.ml_genlist = malloc(sizeof(struct mb_gen_list), M_MBUF, + M_NOWAIT); + if ((mb_list_mbuf.ml_genlist == NULL) || + (mb_list_clust.ml_genlist == NULL)) + goto bad; + + /* + * Initialize condition variables and general container mutex locks. + */ + mtx_init(&mbuf_gen, "mbuf subsystem general lists lock", NULL, 0); + cv_init(&(mb_list_mbuf.ml_genlist->mgl_mstarved), "mbuf pool starved"); + cv_init(&(mb_list_clust.ml_genlist->mgl_mstarved), + "mcluster pool starved"); + mb_list_mbuf.ml_genlist->mb_cont.mc_lock = + mb_list_clust.ml_genlist->mb_cont.mc_lock = &mbuf_gen; + + /* + * Set up the general containers for each object. + */ + mb_list_mbuf.ml_genlist->mb_cont.mc_numowner = + mb_list_clust.ml_genlist->mb_cont.mc_numowner = MB_GENLIST_OWNER; + mb_list_mbuf.ml_genlist->mb_cont.mc_starved = + mb_list_clust.ml_genlist->mb_cont.mc_starved = 0; + mb_list_mbuf.ml_genlist->mb_cont.mc_objcount = + &(mb_statpcpu[MB_GENLIST_OWNER].mb_mbfree); + mb_list_clust.ml_genlist->mb_cont.mc_objcount = + &(mb_statpcpu[MB_GENLIST_OWNER].mb_clfree); + mb_list_mbuf.ml_genlist->mb_cont.mc_numpgs = + &(mb_statpcpu[MB_GENLIST_OWNER].mb_mbpgs); + mb_list_clust.ml_genlist->mb_cont.mc_numpgs = + &(mb_statpcpu[MB_GENLIST_OWNER].mb_clpgs); + mb_list_mbuf.ml_genlist->mb_cont.mc_types = + &(mb_statpcpu[MB_GENLIST_OWNER].mb_mbtypes[0]); + mb_list_clust.ml_genlist->mb_cont.mc_types = NULL; + SLIST_INIT(&(mb_list_mbuf.ml_genlist->mb_cont.mc_bhead)); + SLIST_INIT(&(mb_list_clust.ml_genlist->mb_cont.mc_bhead)); + + /* + * Initialize general mbuf statistics. + */ + mbstat.m_msize = MSIZE; + mbstat.m_mclbytes = MCLBYTES; + mbstat.m_minclsize = MINCLSIZE; + mbstat.m_mlen = MLEN; + mbstat.m_mhlen = MHLEN; + mbstat.m_numtypes = MT_NTYPES; + + /* + * Allocate and initialize PCPU containers. + */ + for (i = 0; i < NCPU; i++) { + if (CPU_ABSENT(i)) + continue; + + mb_list_mbuf.ml_cntlst[i] = malloc(sizeof(struct mb_pcpu_list), + M_MBUF, M_NOWAIT); + mb_list_clust.ml_cntlst[i] = malloc(sizeof(struct mb_pcpu_list), + M_MBUF, M_NOWAIT); + if ((mb_list_mbuf.ml_cntlst[i] == NULL) || + (mb_list_clust.ml_cntlst[i] == NULL)) + goto bad; + + mtx_init(&mbuf_pcpu[i], "mbuf PCPU list lock", NULL, 0); + mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_lock = + mb_list_clust.ml_cntlst[i]->mb_cont.mc_lock = &mbuf_pcpu[i]; + + mb_statpcpu[i].mb_active = 1; + mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_numowner = + mb_list_clust.ml_cntlst[i]->mb_cont.mc_numowner = i; + mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_starved = + mb_list_clust.ml_cntlst[i]->mb_cont.mc_starved = 0; + mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_objcount = + &(mb_statpcpu[i].mb_mbfree); + mb_list_clust.ml_cntlst[i]->mb_cont.mc_objcount = + &(mb_statpcpu[i].mb_clfree); + mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_numpgs = + &(mb_statpcpu[i].mb_mbpgs); + mb_list_clust.ml_cntlst[i]->mb_cont.mc_numpgs = + &(mb_statpcpu[i].mb_clpgs); + mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_types = + &(mb_statpcpu[i].mb_mbtypes[0]); + mb_list_clust.ml_cntlst[i]->mb_cont.mc_types = NULL; + + SLIST_INIT(&(mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_bhead)); + SLIST_INIT(&(mb_list_clust.ml_cntlst[i]->mb_cont.mc_bhead)); + + /* + * Perform initial allocations. + */ + pcpu_cnt = MB_GET_PCPU_LIST_NUM(&mb_list_mbuf, i); + MB_LOCK_CONT(pcpu_cnt); + for (j = 0; j < NMB_MBUF_INIT; j++) { + if (mb_pop_cont(&mb_list_mbuf, M_DONTWAIT, pcpu_cnt) + == NULL) + goto bad; + } + MB_UNLOCK_CONT(pcpu_cnt); + + pcpu_cnt = MB_GET_PCPU_LIST_NUM(&mb_list_clust, i); + MB_LOCK_CONT(pcpu_cnt); + for (j = 0; j < NMB_CLUST_INIT; j++) { + if (mb_pop_cont(&mb_list_clust, M_DONTWAIT, pcpu_cnt) + == NULL) + goto bad; + } + MB_UNLOCK_CONT(pcpu_cnt); + } + + return; +bad: + panic("mbuf_init(): failed to initialize mbuf subsystem!"); +} + +/* + * Populate a given mbuf PCPU container with a bucket full of fresh new + * buffers. Return a pointer to the new bucket (already in the container if + * successful), or return NULL on failure. + * + * LOCKING NOTES: + * PCPU container lock must be held when this is called. + * The lock is dropped here so that we can cleanly call the underlying VM + * code. If we fail, we return with no locks held. If we succeed (i.e., return + * non-NULL), we return with the PCPU lock held, ready for allocation from + * the returned bucket. + */ +static struct mb_bucket * +mb_pop_cont(struct mb_lstmngr *mb_list, int how, struct mb_pcpu_list *cnt_lst) +{ + struct mb_bucket *bucket; + caddr_t p; + int i; + + MB_UNLOCK_CONT(cnt_lst); + /* + * If our object's (finite) map is starved now (i.e., no more address + * space), bail out now. + */ + if (mb_list->ml_mapfull) + return (NULL); + + bucket = malloc(sizeof(struct mb_bucket) + + PAGE_SIZE / mb_list->ml_objsize * sizeof(void *), M_MBUF, + how == M_TRYWAIT ? M_WAITOK : M_NOWAIT); + if (bucket == NULL) + return (NULL); + + p = (caddr_t)kmem_malloc(mb_list->ml_map, PAGE_SIZE, + how == M_TRYWAIT ? M_WAITOK : M_NOWAIT); + if (p == NULL) { + free(bucket, M_MBUF); + if (how == M_TRYWAIT) + mb_list->ml_mapfull = 1; + return (NULL); + } + + bucket->mb_numfree = 0; + mb_list->ml_btable[MB_BUCKET_INDX(p, mb_list)] = bucket; + for (i = 0; i < (PAGE_SIZE / mb_list->ml_objsize); i++) { + bucket->mb_free[i] = p; + bucket->mb_numfree++; + p += mb_list->ml_objsize; + } + + MB_LOCK_CONT(cnt_lst); + bucket->mb_owner = cnt_lst->mb_cont.mc_numowner; + SLIST_INSERT_HEAD(&(cnt_lst->mb_cont.mc_bhead), bucket, mb_blist); + (*(cnt_lst->mb_cont.mc_numpgs))++; + *(cnt_lst->mb_cont.mc_objcount) += bucket->mb_numfree; + + return (bucket); +} + +/* + * Allocate an mbuf-subsystem type object. + * The general case is very easy. Complications only arise if our PCPU + * container is empty. Things get worse if the PCPU container is empty, + * the general container is empty, and we've run out of address space + * in our map; then we try to block if we're willing to (M_TRYWAIT). + */ +static __inline +void * +mb_alloc(struct mb_lstmngr *mb_list, int how, short type) +{ + static int last_report; + struct mb_pcpu_list *cnt_lst; + struct mb_bucket *bucket; + void *m; + + m = NULL; + cnt_lst = MB_GET_PCPU_LIST(mb_list); + MB_LOCK_CONT(cnt_lst); + + if ((bucket = SLIST_FIRST(&(cnt_lst->mb_cont.mc_bhead))) != NULL) { + /* + * This is the easy allocation case. We just grab an object + * from a bucket in the PCPU container. At worst, we + * have just emptied the bucket and so we remove it + * from the container. + */ + MB_GET_OBJECT(m, bucket, cnt_lst); + MB_MBTYPES_INC(cnt_lst, type, 1); + MB_UNLOCK_CONT(cnt_lst); + } else { + struct mb_gen_list *gen_list; + + /* + * This is the less-common more difficult case. We must + * first verify if the general list has anything for us + * and if that also fails, we must allocate a page from + * the map and create a new bucket to place in our PCPU + * container (already locked). If the map is starved then + * we're really in for trouble, as we have to wait on + * the general container's condition variable. + */ + gen_list = MB_GET_GEN_LIST(mb_list); + MB_LOCK_CONT(gen_list); + + if ((bucket = SLIST_FIRST(&(gen_list->mb_cont.mc_bhead))) + != NULL) { + /* + * Give ownership of the bucket to our CPU's + * container, but only actually put the bucket + * in the container if it doesn't become free + * upon removing an mbuf from it. + */ + SLIST_REMOVE_HEAD(&(gen_list->mb_cont.mc_bhead), + mb_blist); + bucket->mb_owner = cnt_lst->mb_cont.mc_numowner; + (*(gen_list->mb_cont.mc_numpgs))--; + (*(cnt_lst->mb_cont.mc_numpgs))++; + *(gen_list->mb_cont.mc_objcount) -= bucket->mb_numfree; + bucket->mb_numfree--; + m = bucket->mb_free[(bucket->mb_numfree)]; + if (bucket->mb_numfree == 0) { + SLIST_NEXT(bucket, mb_blist) = NULL; + bucket->mb_owner |= MB_BUCKET_FREE; + } else { + SLIST_INSERT_HEAD(&(cnt_lst->mb_cont.mc_bhead), + bucket, mb_blist); + *(cnt_lst->mb_cont.mc_objcount) += + bucket->mb_numfree; + } + MB_UNLOCK_CONT(gen_list); + MB_MBTYPES_INC(cnt_lst, type, 1); + MB_UNLOCK_CONT(cnt_lst); + } else { + /* + * We'll have to allocate a new page. + */ + MB_UNLOCK_CONT(gen_list); + bucket = mb_pop_cont(mb_list, how, cnt_lst); + if (bucket != NULL) { + MB_GET_OBJECT(m, bucket, cnt_lst); + MB_MBTYPES_INC(cnt_lst, type, 1); + MB_UNLOCK_CONT(cnt_lst); + } else { + if (how == M_TRYWAIT) { + /* + * Absolute worst-case scenario. + * We block if we're willing to, but + * only after trying to steal from + * other lists. + */ + m = mb_alloc_wait(mb_list, type); + } else { + /* XXX: No consistency. */ + mbstat.m_drops++; + + if (ticks < last_report || + (ticks - last_report) >= hz) { + last_report = ticks; + printf( +"All mbufs exhausted, please see tuning(7).\n"); +/* XXX: Actually could be clusters, but it gets the point across. */ + } + + } + } + } + } + + return (m); +} + +/* + * This is the worst-case scenario called only if we're allocating with + * M_TRYWAIT. We first drain all the protocols, then try to find an mbuf + * by looking in every PCPU container. If we're still unsuccesful, we + * try the general container one last time and possibly block on our + * starved cv. + */ +static void * +mb_alloc_wait(struct mb_lstmngr *mb_list, short type) +{ + struct mb_pcpu_list *cnt_lst; + struct mb_gen_list *gen_list; + struct mb_bucket *bucket; + void *m; + int i, cv_ret; + + /* + * Try to reclaim mbuf-related objects (mbufs, clusters). + */ + mb_reclaim(); + + /* + * Cycle all the PCPU containers. Increment starved counts if found + * empty. + */ + for (i = 0; i < NCPU; i++) { + if (CPU_ABSENT(i)) + continue; + cnt_lst = MB_GET_PCPU_LIST_NUM(mb_list, i); + MB_LOCK_CONT(cnt_lst); + + /* + * If container is non-empty, get a single object from it. + * If empty, increment starved count. + */ + if ((bucket = SLIST_FIRST(&(cnt_lst->mb_cont.mc_bhead))) != + NULL) { + MB_GET_OBJECT(m, bucket, cnt_lst); + MB_MBTYPES_INC(cnt_lst, type, 1); + MB_UNLOCK_CONT(cnt_lst); + mbstat.m_wait++; /* XXX: No consistency. */ + return (m); + } else + cnt_lst->mb_cont.mc_starved++; + + MB_UNLOCK_CONT(cnt_lst); + } + + /* + * We're still here, so that means it's time to get the general + * container lock, check it one more time (now that mb_reclaim() + * has been called) and if we still get nothing, block on the cv. + */ + gen_list = MB_GET_GEN_LIST(mb_list); + MB_LOCK_CONT(gen_list); + if ((bucket = SLIST_FIRST(&(gen_list->mb_cont.mc_bhead))) != NULL) { + MB_GET_OBJECT(m, bucket, gen_list); + MB_MBTYPES_INC(gen_list, type, 1); + MB_UNLOCK_CONT(gen_list); + mbstat.m_wait++; /* XXX: No consistency. */ + return (m); + } + + gen_list->mb_cont.mc_starved++; + cv_ret = cv_timedwait(&(gen_list->mgl_mstarved), + gen_list->mb_cont.mc_lock, mbuf_wait); + gen_list->mb_cont.mc_starved--; + + if ((cv_ret == 0) && + ((bucket = SLIST_FIRST(&(gen_list->mb_cont.mc_bhead))) != NULL)) { + MB_GET_OBJECT(m, bucket, gen_list); + MB_MBTYPES_INC(gen_list, type, 1); + mbstat.m_wait++; /* XXX: No consistency. */ + } else { + mbstat.m_drops++; /* XXX: No consistency. */ + m = NULL; + } + + MB_UNLOCK_CONT(gen_list); + + return (m); +} + +/*- + * Free an object to its rightful container. + * In the very general case, this operation is really very easy. + * Complications arise primarily if: + * (a) We've hit the high limit on number of free objects allowed in + * our PCPU container. + * (b) We're in a critical situation where our container has been + * marked 'starved' and we need to issue wakeups on the starved + * condition variable. + * (c) Minor (odd) cases: our bucket has migrated while we were + * waiting for the lock; our bucket is in the general container; + * our bucket is empty. + */ +static __inline +void +mb_free(struct mb_lstmngr *mb_list, void *m, short type) +{ + struct mb_pcpu_list *cnt_lst; + struct mb_gen_list *gen_list; + struct mb_bucket *bucket; + u_int owner; + + bucket = mb_list->ml_btable[MB_BUCKET_INDX(m, mb_list)]; + + /* + * Make sure that if after we lock the bucket's present container the + * bucket has migrated, that we drop the lock and get the new one. + */ +retry_lock: + owner = bucket->mb_owner & ~MB_BUCKET_FREE; + switch (owner) { + case MB_GENLIST_OWNER: + gen_list = MB_GET_GEN_LIST(mb_list); + MB_LOCK_CONT(gen_list); + if (owner != (bucket->mb_owner & ~MB_BUCKET_FREE)) { + MB_UNLOCK_CONT(gen_list); + goto retry_lock; + } + + /* + * If we're intended for the general container, this is + * real easy: no migrating required. The only `bogon' + * is that we're now contending with all the threads + * dealing with the general list, but this is expected. + */ + MB_PUT_OBJECT(m, bucket, gen_list); + MB_MBTYPES_DEC(gen_list, type, 1); + if (gen_list->mb_cont.mc_starved > 0) + cv_signal(&(gen_list->mgl_mstarved)); + MB_UNLOCK_CONT(gen_list); + break; + + default: + cnt_lst = MB_GET_PCPU_LIST_NUM(mb_list, owner); + MB_LOCK_CONT(cnt_lst); + if (owner != (bucket->mb_owner & ~MB_BUCKET_FREE)) { + MB_UNLOCK_CONT(cnt_lst); + goto retry_lock; + } + + MB_PUT_OBJECT(m, bucket, cnt_lst); + MB_MBTYPES_DEC(cnt_lst, type, 1); + + if (cnt_lst->mb_cont.mc_starved > 0) { + /* + * This is a tough case. It means that we've + * been flagged at least once to indicate that + * we're empty, and that the system is in a critical + * situation, so we ought to migrate at least one + * bucket over to the general container. + * There may or may not be a thread blocking on + * the starved condition variable, but chances + * are that one will eventually come up soon so + * it's better to migrate now than never. + */ + gen_list = MB_GET_GEN_LIST(mb_list); + MB_LOCK_CONT(gen_list); + KASSERT((bucket->mb_owner & MB_BUCKET_FREE) != 0, + ("mb_free: corrupt bucket %p\n", bucket)); + SLIST_INSERT_HEAD(&(gen_list->mb_cont.mc_bhead), + bucket, mb_blist); + bucket->mb_owner = MB_GENLIST_OWNER; + (*(cnt_lst->mb_cont.mc_objcount))--; + (*(gen_list->mb_cont.mc_objcount))++; + (*(cnt_lst->mb_cont.mc_numpgs))--; + (*(gen_list->mb_cont.mc_numpgs))++; + + /* + * Determine whether or not to keep transferring + * buckets to the general list or whether we've + * transferred enough already. + * We realize that although we may flag another + * bucket to be migrated to the general container + * that in the meantime, the thread that was + * blocked on the cv is already woken up and + * long gone. But in that case, the worst + * consequence is that we will end up migrating + * one bucket too many, which is really not a big + * deal, especially if we're close to a critical + * situation. + */ + if (gen_list->mb_cont.mc_starved > 0) { + cnt_lst->mb_cont.mc_starved--; + cv_signal(&(gen_list->mgl_mstarved)); + } else + cnt_lst->mb_cont.mc_starved = 0; + + MB_UNLOCK_CONT(gen_list); + MB_UNLOCK_CONT(cnt_lst); + break; + } + + if (*(cnt_lst->mb_cont.mc_objcount) > *(mb_list->ml_wmhigh)) { + /* + * We've hit the high limit of allowed numbers of mbufs + * on this PCPU list. We must now migrate a bucket + * over to the general container. + */ + gen_list = MB_GET_GEN_LIST(mb_list); + MB_LOCK_CONT(gen_list); + if ((bucket->mb_owner & MB_BUCKET_FREE) == 0) { + bucket = + SLIST_FIRST(&(cnt_lst->mb_cont.mc_bhead)); + SLIST_REMOVE_HEAD(&(cnt_lst->mb_cont.mc_bhead), + mb_blist); + } + SLIST_INSERT_HEAD(&(gen_list->mb_cont.mc_bhead), + bucket, mb_blist); + bucket->mb_owner = MB_GENLIST_OWNER; + *(cnt_lst->mb_cont.mc_objcount) -= bucket->mb_numfree; + *(gen_list->mb_cont.mc_objcount) += bucket->mb_numfree; + (*(cnt_lst->mb_cont.mc_numpgs))--; + (*(gen_list->mb_cont.mc_numpgs))++; + + /* + * While we're at it, transfer some of the mbtypes + * "count load" onto the general list's mbtypes + * array, seeing as how we're moving the bucket + * there now, meaning that the freeing of objects + * there will now decrement the _general list's_ + * mbtypes counters, and no longer our PCPU list's + * mbtypes counters. We do this for the type presently + * being freed in an effort to keep the mbtypes + * counters approximately balanced across all lists. + */ + MB_MBTYPES_DEC(cnt_lst, type, (PAGE_SIZE / + mb_list->ml_objsize) - bucket->mb_numfree); + MB_MBTYPES_INC(gen_list, type, (PAGE_SIZE / + mb_list->ml_objsize) - bucket->mb_numfree); + + MB_UNLOCK_CONT(gen_list); + MB_UNLOCK_CONT(cnt_lst); + break; + } + + if (bucket->mb_owner & MB_BUCKET_FREE) { + SLIST_INSERT_HEAD(&(cnt_lst->mb_cont.mc_bhead), + bucket, mb_blist); + bucket->mb_owner = cnt_lst->mb_cont.mc_numowner; + } + + MB_UNLOCK_CONT(cnt_lst); + break; + } +} + +/* + * Drain protocols in hopes to free up some resources. + * + * LOCKING NOTES: + * No locks should be held when this is called. The drain routines have to + * presently acquire some locks which raises the possibility of lock order + * violation if we're holding any mutex if that mutex is acquired in reverse + * order relative to one of the locks in the drain routines. + */ +static void +mb_reclaim(void) +{ + struct domain *dp; + struct protosw *pr; + +/* + * XXX: Argh, we almost always trip here with witness turned on now-a-days + * XXX: because we often come in with Giant held. For now, there's no way + * XXX: to avoid this. + */ +#ifdef WITNESS + KASSERT(witness_list(curthread) == 0, + ("mb_reclaim() called with locks held")); +#endif + + mbstat.m_drain++; /* XXX: No consistency. */ + + for (dp = domains; dp != NULL; dp = dp->dom_next) + for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++) + if (pr->pr_drain != NULL) + (*pr->pr_drain)(); +} + +/* + * Local mbuf & cluster alloc macros and routines. + * Local macro and function names begin with an underscore ("_"). + */ +static void _mclfree(struct mbuf *); + +#define _m_get(m, how, type) do { \ + (m) = (struct mbuf *)mb_alloc(&mb_list_mbuf, (how), (type)); \ + if ((m) != NULL) { \ + (m)->m_type = (type); \ + (m)->m_next = NULL; \ + (m)->m_nextpkt = NULL; \ + (m)->m_data = (m)->m_dat; \ + (m)->m_flags = 0; \ + } \ +} while (0) + +#define _m_gethdr(m, how, type) do { \ + (m) = (struct mbuf *)mb_alloc(&mb_list_mbuf, (how), (type)); \ + if ((m) != NULL) { \ + (m)->m_type = (type); \ + (m)->m_next = NULL; \ + (m)->m_nextpkt = NULL; \ + (m)->m_data = (m)->m_pktdat; \ + (m)->m_flags = M_PKTHDR; \ + (m)->m_pkthdr.rcvif = NULL; \ + (m)->m_pkthdr.csum_flags = 0; \ + (m)->m_pkthdr.aux = NULL; \ + } \ +} while (0) + +/* XXX: Check for M_PKTHDR && m_pkthdr.aux is bogus... please fix (see KAME). */ +#define _m_free(m, n) do { \ + (n) = (m)->m_next; \ + if ((m)->m_flags & M_EXT) \ + MEXTFREE((m)); \ + if (((m)->m_flags & M_PKTHDR) != 0 && (m)->m_pkthdr.aux) { \ + m_freem((m)->m_pkthdr.aux); \ + (m)->m_pkthdr.aux = NULL; \ + } \ + mb_free(&mb_list_mbuf, (m), (m)->m_type); \ +} while (0) + +#define _mext_init_ref(m) do { \ + (m)->m_ext.ref_cnt = malloc(sizeof(u_int), M_MBUF, M_NOWAIT); \ + if ((m)->m_ext.ref_cnt != NULL) { \ + *((m)->m_ext.ref_cnt) = 0; \ + MEXT_ADD_REF((m)); \ + } \ +} while (0) + +#define _mext_dealloc_ref(m) \ + free((m)->m_ext.ref_cnt, M_MBUF) + +void +_mext_free(struct mbuf *mb) +{ + + if (mb->m_ext.ext_type == EXT_CLUSTER) + mb_free(&mb_list_clust, (caddr_t)mb->m_ext.ext_buf, MT_NOTMBUF); + else + (*(mb->m_ext.ext_free))(mb->m_ext.ext_buf, mb->m_ext.ext_args); + _mext_dealloc_ref(mb); +} + +/* + * We only include this here to avoid making m_clget() excessively large + * due to too much inlined code. + */ +static void +_mclfree(struct mbuf *mb) +{ + + mb_free(&mb_list_clust, (caddr_t)mb->m_ext.ext_buf, MT_NOTMBUF); + mb->m_ext.ext_buf = NULL; +} + +/* + * Exported space allocation and de-allocation routines. + */ +struct mbuf * +m_get(int how, int type) +{ + struct mbuf *mb; + + _m_get(mb, how, type); + return (mb); +} + +struct mbuf * +m_gethdr(int how, int type) +{ + struct mbuf *mb; + + _m_gethdr(mb, how, type); + return (mb); +} + +struct mbuf * +m_get_clrd(int how, int type) +{ + struct mbuf *mb; + + _m_get(mb, how, type); + if (mb != NULL) + bzero(mtod(mb, caddr_t), MLEN); + return (mb); +} + +struct mbuf * +m_gethdr_clrd(int how, int type) +{ + struct mbuf *mb; + + _m_gethdr(mb, how, type); + if (mb != NULL) + bzero(mtod(mb, caddr_t), MHLEN); + return (mb); +} + +struct mbuf * +m_free(struct mbuf *mb) +{ + struct mbuf *nb; + + _m_free(mb, nb); + return (nb); +} + +void +m_clget(struct mbuf *mb, int how) +{ + + mb->m_ext.ext_buf = (caddr_t)mb_alloc(&mb_list_clust, how, MT_NOTMBUF); + if (mb->m_ext.ext_buf != NULL) { + _mext_init_ref(mb); + if (mb->m_ext.ref_cnt == NULL) + _mclfree(mb); + else { + mb->m_data = mb->m_ext.ext_buf; + mb->m_flags |= M_EXT; + mb->m_ext.ext_free = NULL; + mb->m_ext.ext_args = NULL; + mb->m_ext.ext_size = MCLBYTES; + mb->m_ext.ext_type = EXT_CLUSTER; + } + } +} + +void +m_extadd(struct mbuf *mb, caddr_t buf, u_int size, + void (*freef)(void *, void *), void *args, short flags, int type) +{ + + _mext_init_ref(mb); + if (mb->m_ext.ref_cnt != NULL) { + mb->m_flags |= (M_EXT | flags); + mb->m_ext.ext_buf = buf; + mb->m_data = mb->m_ext.ext_buf; + mb->m_ext.ext_size = size; + mb->m_ext.ext_free = freef; + mb->m_ext.ext_args = args; + mb->m_ext.ext_type = type; + } +} + +/* + * Change type for mbuf `mb'; this is a relatively expensive operation and + * should be avoided. + */ +void +m_chtype(struct mbuf *mb, short new_type) +{ + struct mb_gen_list *gen_list; + + gen_list = MB_GET_GEN_LIST(&mb_list_mbuf); + MB_LOCK_CONT(gen_list); + MB_MBTYPES_DEC(gen_list, mb->m_type, 1); + MB_MBTYPES_INC(gen_list, new_type, 1); + MB_UNLOCK_CONT(gen_list); + mb->m_type = new_type; +} |
