75e1056f5c
Peter Zijlstra found a bug in the way softirq time is accounted in VIRT_CPU_ACCOUNTING on this thread: http://lkml.indiana.edu/hypermail//linux/kernel/1009.2/01366.html The problem is, softirq processing uses local_bh_disable internally. There is no way, later in the flow, to differentiate between whether softirq is being processed or is it just that bh has been disabled. So, a hardirq when bh is disabled results in time being wrongly accounted as softirq. Looking at the code a bit more, the problem exists in !VIRT_CPU_ACCOUNTING as well. As account_system_time() in normal tick based accouting also uses softirq_count, which will be set even when not in softirq with bh disabled. Peter also suggested solution of using 2*SOFTIRQ_OFFSET as irq count for local_bh_{disable,enable} and using just SOFTIRQ_OFFSET while softirq processing. The patch below does that and adds API in_serving_softirq() which returns whether we are currently processing softirq or not. Also changes one of the usages of softirq_count in net/sched/cls_cgroup.c to in_serving_softirq. Looks like many usages of in_softirq really want in_serving_softirq. Those changes can be made individually on a case by case basis. Signed-off-by: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1286237003-12406-2-git-send-email-venki@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> |
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| .. | ||
| Kconfig | ||
| Makefile | ||
| act_api.c | ||
| act_gact.c | ||
| act_ipt.c | ||
| act_mirred.c | ||
| act_nat.c | ||
| act_pedit.c | ||
| act_police.c | ||
| act_simple.c | ||
| act_skbedit.c | ||
| cls_api.c | ||
| cls_basic.c | ||
| cls_cgroup.c | ||
| cls_flow.c | ||
| cls_fw.c | ||
| cls_route.c | ||
| cls_rsvp.c | ||
| cls_rsvp.h | ||
| cls_rsvp6.c | ||
| cls_tcindex.c | ||
| cls_u32.c | ||
| em_cmp.c | ||
| em_meta.c | ||
| em_nbyte.c | ||
| em_text.c | ||
| em_u32.c | ||
| ematch.c | ||
| sch_api.c | ||
| sch_atm.c | ||
| sch_blackhole.c | ||
| sch_cbq.c | ||
| sch_drr.c | ||
| sch_dsmark.c | ||
| sch_fifo.c | ||
| sch_generic.c | ||
| sch_gred.c | ||
| sch_hfsc.c | ||
| sch_htb.c | ||
| sch_ingress.c | ||
| sch_mq.c | ||
| sch_multiq.c | ||
| sch_netem.c | ||
| sch_prio.c | ||
| sch_red.c | ||
| sch_sfq.c | ||
| sch_tbf.c | ||
| sch_teql.c | ||