diff options
Diffstat (limited to 'sys/vm/vm_glue.c')
| -rw-r--r-- | sys/vm/vm_glue.c | 138 |
1 files changed, 95 insertions, 43 deletions
diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c index 9e43a3f..851c733 100644 --- a/sys/vm/vm_glue.c +++ b/sys/vm/vm_glue.c @@ -77,6 +77,7 @@ __FBSDID("$FreeBSD$"); #include <sys/sx.h> #include <sys/sysctl.h> +#include <sys/eventhandler.h> #include <sys/kernel.h> #include <sys/ktr.h> #include <sys/unistd.h> @@ -308,6 +309,20 @@ vm_imgact_unmap_page(struct sf_buf *sf) vm_page_unlock_queues(); } +struct kstack_cache_entry { + vm_object_t ksobj; + struct kstack_cache_entry *next_ks_entry; +}; + +static struct kstack_cache_entry *kstack_cache; +static int kstack_cache_size = 128; +static int kstacks; +static struct mtx kstack_cache_mtx; +SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0, + ""); +SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0, + ""); + #ifndef KSTACK_MAX_PAGES #define KSTACK_MAX_PAGES 32 #endif @@ -323,6 +338,7 @@ vm_thread_new(struct thread *td, int pages) vm_object_t ksobj; vm_offset_t ks; vm_page_t m, ma[KSTACK_MAX_PAGES]; + struct kstack_cache_entry *ks_ce; int i; /* Bounds check */ @@ -330,6 +346,22 @@ vm_thread_new(struct thread *td, int pages) pages = KSTACK_PAGES; else if (pages > KSTACK_MAX_PAGES) pages = KSTACK_MAX_PAGES; + + if (pages == KSTACK_PAGES) { + mtx_lock(&kstack_cache_mtx); + if (kstack_cache != NULL) { + ks_ce = kstack_cache; + kstack_cache = ks_ce->next_ks_entry; + mtx_unlock(&kstack_cache_mtx); + + td->td_kstack_obj = ks_ce->ksobj; + td->td_kstack = (vm_offset_t)ks_ce; + td->td_kstack_pages = KSTACK_PAGES; + return (1); + } + mtx_unlock(&kstack_cache_mtx); + } + /* * Allocate an object for the kstack. */ @@ -345,7 +377,8 @@ vm_thread_new(struct thread *td, int pages) vm_object_deallocate(ksobj); return (0); } - + + atomic_add_int(&kstacks, 1); if (KSTACK_GUARD_PAGES != 0) { pmap_qremove(ks, KSTACK_GUARD_PAGES); ks += KSTACK_GUARD_PAGES * PAGE_SIZE; @@ -376,20 +409,13 @@ vm_thread_new(struct thread *td, int pages) return (1); } -/* - * Dispose of a thread's kernel stack. - */ -void -vm_thread_dispose(struct thread *td) +static void +vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages) { - vm_object_t ksobj; - vm_offset_t ks; vm_page_t m; - int i, pages; + int i; - pages = td->td_kstack_pages; - ksobj = td->td_kstack_obj; - ks = td->td_kstack; + atomic_add_int(&kstacks, -1); pmap_qremove(ks, pages); VM_OBJECT_LOCK(ksobj); for (i = 0; i < pages; i++) { @@ -405,9 +431,66 @@ vm_thread_dispose(struct thread *td) vm_object_deallocate(ksobj); kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); +} + +/* + * Dispose of a thread's kernel stack. + */ +void +vm_thread_dispose(struct thread *td) +{ + vm_object_t ksobj; + vm_offset_t ks; + struct kstack_cache_entry *ks_ce; + int pages; + + pages = td->td_kstack_pages; + ksobj = td->td_kstack_obj; + ks = td->td_kstack; td->td_kstack = 0; + td->td_kstack_pages = 0; + if (pages == KSTACK_PAGES && kstacks <= kstack_cache_size) { + ks_ce = (struct kstack_cache_entry *)ks; + ks_ce->ksobj = ksobj; + mtx_lock(&kstack_cache_mtx); + ks_ce->next_ks_entry = kstack_cache; + kstack_cache = ks_ce; + mtx_unlock(&kstack_cache_mtx); + return; + } + vm_thread_stack_dispose(ksobj, ks, pages); } +static void +vm_thread_stack_lowmem(void *nulll) +{ + struct kstack_cache_entry *ks_ce, *ks_ce1; + + mtx_lock(&kstack_cache_mtx); + ks_ce = kstack_cache; + kstack_cache = NULL; + mtx_unlock(&kstack_cache_mtx); + + while (ks_ce != NULL) { + ks_ce1 = ks_ce; + ks_ce = ks_ce->next_ks_entry; + + vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1, + KSTACK_PAGES); + } +} + +static void +kstack_cache_init(void *nulll) +{ + + EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL, + EVENTHANDLER_PRI_ANY); +} + +MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF); +SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL); + /* * Allow a thread's kernel stack to be paged out. */ @@ -468,37 +551,6 @@ vm_thread_swapin(struct thread *td) } /* - * Set up a variable-sized alternate kstack. - */ -int -vm_thread_new_altkstack(struct thread *td, int pages) -{ - - td->td_altkstack = td->td_kstack; - td->td_altkstack_obj = td->td_kstack_obj; - td->td_altkstack_pages = td->td_kstack_pages; - - return (vm_thread_new(td, pages)); -} - -/* - * Restore the original kstack. - */ -void -vm_thread_dispose_altkstack(struct thread *td) -{ - - vm_thread_dispose(td); - - td->td_kstack = td->td_altkstack; - td->td_kstack_obj = td->td_altkstack_obj; - td->td_kstack_pages = td->td_altkstack_pages; - td->td_altkstack = 0; - td->td_altkstack_obj = NULL; - td->td_altkstack_pages = 0; -} - -/* * Implement fork's actions on an address space. * Here we arrange for the address space to be copied or referenced, * allocate a user struct (pcb and kernel stack), then call the |
