From: Peter Zijlstra <peterz@infradead.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Yuanhan Liu <yuanhan.liu@linux.intel.com>,
mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org,
tglx@linutronix.de, linux-tip-commits@vger.kernel.org,
Fengguang Wu <fengguang.wu@intel.com>,
Huang Ying <ying.huang@intel.com>,
lkp@linux.intel.com
Subject: Re: [PATCH] sched: Revert need_resched() to look at TIF_NEED_RESCHED
Date: Tue, 10 Dec 2013 16:52:46 +0100 [thread overview]
Message-ID: <20131210155246.GI12849@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <87y53ubk6a.fsf@linux.vnet.ibm.com>
On Mon, Dec 09, 2013 at 12:11:33PM +0530, Aneesh Kumar K.V wrote:
> Peter Zijlstra <peterz@infradead.org> writes:
>
> > Subject: sched: Revert need_resched() to look at TIF_NEED_RESCHED
> > From: Peter Zijlstra <peterz@infradead.org>
> > Date: Fri Sep 27 17:20:30 CEST 2013
> >
> > Yuanhan reported a serious throughput regression in his pigz
> > benchmark. Using the ftrace patch I found that several idle paths
> > need more TLC before we can switch the generic need_resched() over to
> > preempt_need_resched.
> >
> > The preemption paths benefit most from preempt_need_resched and do
> > indeed use it; all other need_resched() users don't really care that
> > much so reverting need_resched() back to tif_need_resched() is the
> > simple and safe solution.
> >
> > Reported-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> > Signed-off-by: Peter Zijlstra <peterz@infradead.org>
>
> I guess we still need to fix should_resched() I am hitting the below
> with upstream
>
>
> BUG: soft lockup - CPU#0 stuck for 23s! [qemu-system-ppc:4394]
> Modules linked in:
> CPU: 0 PID: 4394 Comm: qemu-system-ppc Not tainted 3.13.0-rc3+ #98
> task: c0000001d0788400 ti: c0000001dca00000 task.ti: c0000001dca00000
> NIP: c00000000082dd80 LR: c000000000081ae0 CTR: c000000000062ba0
> REGS: c0000001dca02f70 TRAP: 0901 Not tainted (3.13.0-rc3+)
> MSR: 8000000000009032 <SF,EE,ME,IR,DR,RI> CR: 24822024 XER: 00000000
> CFAR: c000000000081adc SOFTE: 1
> GPR00: c000000000081ae0 c0000001dca031f0 c000000000d67ab0 0000000000000001
> GPR04: 0000000071000002 0000000000000001 00000189a0d786b7 00000000018c0000
> GPR08: 0000000000000001 0000000000000000 0000000000000000 c000000000da0000
> GPR12: 0000000000000c00 c00000000fef0000
> NIP [c00000000082dd80] ._cond_resched+0x0/0x40
> LR [c000000000081ae0] .kvmppc_prepare_to_enter+0x2a0/0x2e0
> Call Trace:
> [c0000001dca031f0] [c000000000081ae0] .kvmppc_prepare_to_enter+0x2a0/0x2e0 (unreliable)
> [c0000001dca03290] [c00000000008f2cc] .kvmppc_handle_exit_pr+0xec/0xa40
> [c0000001dca03340] [c0000000000918c4] kvm_start_lightweight+0xac/0xbc
> [c0000001dca03510] [c00000000008efe0] .kvmppc_vcpu_run_pr+0x130/0x2a0
> [c0000001dca039e0] [c0000000000855bc] .kvmppc_vcpu_run+0x2c/0x40
> [c0000001dca03a50] [c000000000082c94] .kvm_arch_vcpu_ioctl_run+0x54/0x1b0
> [c0000001dca03ae0] [c00000000007d5f8] .kvm_vcpu_ioctl+0x478/0x740
> [c0000001dca03ca0] [c000000000218864] .do_vfs_ioctl+0x4a4/0x760
> [c0000001dca03d80] [c000000000218b78] .SyS_ioctl+0x58/0xb0
> [c0000001dca03e30] [c000000000009e58] syscall_exit+0x0/0x98
> Instruction dump:
> e92d0260 e94911c0 812a0004 5529f07e 5529103e 912a0004 38210080 e8010010
> ebc1fff0 ebe1fff8 7c0803a6 4e800020 <7c0802a6> 38600000 f8010010 f821ff91
>
>
> The revert which Alexander tried had those
>
> http://mid.gmane.org/20131128132641.GP10022@twins.programming.kicks-ass.net
-ENOPARSE..
next prev parent reply other threads:[~2013-12-10 15:53 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-25 16:38 [tip:sched/core] sched: Add NEED_RESCHED to the preempt_count tip-bot for Peter Zijlstra
2013-09-27 9:14 ` Yuanhan Liu
2013-09-27 11:57 ` Peter Zijlstra
2013-09-27 12:13 ` Fengguang Wu
2013-09-27 12:20 ` Fengguang Wu
2013-09-27 15:29 ` [PATCH] ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED Peter Zijlstra
2013-10-04 8:09 ` Peter Zijlstra
2013-10-04 14:53 ` Steven Rostedt
2013-10-04 15:16 ` Peter Zijlstra
2013-10-04 15:25 ` Steven Rostedt
2013-10-04 15:28 ` Peter Zijlstra
2013-10-04 15:57 ` Steven Rostedt
2013-10-04 16:28 ` Peter Zijlstra
2013-11-11 17:52 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2013-11-06 16:37 ` [PATCH] " Steven Rostedt
2013-11-06 16:45 ` Peter Zijlstra
2013-11-06 16:58 ` Steven Rostedt
2013-11-06 17:23 ` Peter Zijlstra
2013-09-27 15:30 ` [PATCH] sched: Revert need_resched() to look at TIF_NEED_RESCHED Peter Zijlstra
2013-09-28 8:28 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2013-12-09 6:41 ` [PATCH] " Aneesh Kumar K.V
2013-12-10 15:52 ` Peter Zijlstra [this message]
2013-11-28 13:26 ` [PATCH] sched: Remove PREEMPT_NEED_RESCHED from generic code Peter Zijlstra
2013-11-28 15:24 ` Alexander Graf
2013-12-09 6:29 ` Benjamin Herrenschmidt
2013-12-12 9:51 ` [tip:sched/urgent] " tip-bot for Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20131210155246.GI12849@twins.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=aneesh.kumar@linux.vnet.ibm.com \
--cc=fengguang.wu@intel.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=lkp@linux.intel.com \
--cc=mingo@kernel.org \
--cc=tglx@linutronix.de \
--cc=ying.huang@intel.com \
--cc=yuanhan.liu@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.