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* sched, net: Fixup busy_loop_us_clock()Peter Zijlstra2014-01-131-18/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The only valid use of preempt_enable_no_resched() is if the very next line is schedule() or if we know preemption cannot actually be enabled by that statement due to known more preempt_count 'refs'. This busy_poll stuff looks to be completely and utterly broken, sched_clock() can return utter garbage with interrupts enabled (rare but still) and it can drift unbounded between CPUs. This means that if you get preempted/migrated and your new CPU is years behind on the previous CPU we get to busy spin for a _very_ long time. There is a _REASON_ sched_clock() warns about preemptability - papering over it with a preempt_disable()/preempt_enable_no_resched() is just terminal brain damage on so many levels. Replace sched_clock() usage with local_clock() which has a bounded drift between CPUs (<2 jiffies). There is a further problem with the entire busy wait poll thing in that the spin time is additive to the syscall timeout, not inclusive. Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: David S. Miller <davem@davemloft.net> Cc: rui.zhang@intel.com Cc: jacob.jun.pan@linux.intel.com Cc: Mike Galbraith <bitbucket@online.de> Cc: hpa@zytor.com Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: lenb@kernel.org Cc: rjw@rjwysocki.net Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20131119151338.GF3694@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
* net: add cpu_relax to busy poll loopEliezer Tamir2013-08-281-0/+1
| | | | | | | | | | | | Add a cpu_relaxt to sk_busy_loop. Julie Cummings reported performance issues when hyperthreading is on. Arjan van de Ven observed that we should have a cpu_relax() in the busy poll loop. Reported-by: Julie Cummings <julie.a.cummings@intel.com> Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: rename busy poll MIB counterEliezer Tamir2013-08-091-1/+1
| | | | | | | | | | | | Rename mib counter from "low latency" to "busy poll" v1 also moved the counter to the ip MIB (suggested by Shawn Bohrer) Eric Dumazet suggested that the current location is better. So v2 just renames the counter to fit the new naming convention. Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* busy_poll: cleanup do-nothing placeholdersEliezer Tamir2013-08-041-5/+0
| | | | | | | | | | | | When renaming ll_poll to busy poll, I introduced a typo in the name of the do-nothing placeholder for sk_busy_loop and called it sk_busy_poll. This broke compile when busy poll was not configured. Cong Wang submitted a patch to fixed that. This patch removes the now redundant, misspelled placeholder. Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: rename CONFIG_NET_LL_RX_POLL to CONFIG_NET_RX_BUSY_POLLCong Wang2013-08-011-3/+3
| | | | | | | | | | Eliezer renames several *ll_poll to *busy_poll, but forgets CONFIG_NET_LL_RX_POLL, so in case of confusion, rename it too. Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Cong Wang <amwang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: fix a compile error when CONFIG_NET_LL_RX_POLL is not setCong Wang2013-08-011-0/+5
| | | | | | | | | | | | | | When CONFIG_NET_LL_RX_POLL is not set, I got: net/socket.c: In function ‘sock_poll’: net/socket.c:1165:4: error: implicit declaration of function ‘sk_busy_loop’ [-Werror=implicit-function-declaration] Fix this by adding a nop when !CONFIG_NET_LL_RX_POLL. Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Cong Wang <amwang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: rename busy poll socket op and globalsEliezer Tamir2013-07-101-4/+4
| | | | | | | | | | | | | Rename LL_SO to BUSY_POLL_SO Rename sysctl_net_ll_{read,poll} to sysctl_busy_{read,poll} Fix up users of these variables. Fix documentation for sysctl. a patch for the socket.7 man page will follow separately, because of limitations of my mail setup. Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: rename ll methods to busy-pollEliezer Tamir2013-07-101-10/+12
| | | | | | | | | | | Rename ndo_ll_poll to ndo_busy_poll. Rename sk_mark_ll to sk_mark_napi_id. Rename skb_mark_ll to skb_mark_napi_id. Correct all useres of these functions. Update comments and defines in include/net/busy_poll.h Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: rename include/net/ll_poll.h to include/net/busy_poll.hEliezer Tamir2013-07-101-0/+183
Rename the file and correct all the places where it is included. Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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