From: Peter Zijlstra <peterz@infradead.org>
To: piotr@hosowicz.com
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org, Jens Axboe <jens.axboe@oracle.com>,
Divyesh Shah <dpshah@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: BUG: using smp_processor_id() in preemptible [00000000] code: icedove-bin/5449
Date: Tue, 25 May 2010 12:00:55 +0200 [thread overview]
Message-ID: <1274781655.5882.765.camel@twins> (raw)
In-Reply-To: <4BFB9F0A.9040803@example.com>
On Tue, 2010-05-25 at 11:57 +0200, Piotr Hosowicz wrote:
> On 25.05.2010 11:43, Ingo Molnar wrote:
>
> > This doesnt fix the whole issue. cpu_clock() is local, while the measurements
> > done in the blk code are global ...
> >
> > While the warning is fixed this way, the far more serious issue is still
> > there: time can go backwards if two points of time measurement are on
> > different CPUs and can mess up the statistics with negative values, etc...
>
> How serious is this? Can it damage my data? I ask because the machine is
> my private computer, not any test machine.
I'm not sure, since I didn't really look what they use the timestamps
for, but a guess would say your data is safe, it might schedule the io
funny, but it should not compromise integrity. At best its used purely
for statistics and not even behaviour is affected.
next prev parent reply other threads:[~2010-05-25 10:01 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-24 3:03 BUG: using smp_processor_id() in preemptible [00000000] code: icedove-bin/5449 Piotr Hosowicz
2010-05-24 17:22 ` Piotr Hosowicz
2010-05-25 8:50 ` Peter Zijlstra
2010-05-25 9:42 ` Piotr Hosowicz
2010-05-25 9:45 ` Peter Zijlstra
2010-05-25 9:43 ` Ingo Molnar
2010-05-25 9:47 ` Peter Zijlstra
2010-05-25 9:51 ` Peter Zijlstra
2010-05-25 9:57 ` Piotr Hosowicz
2010-05-25 10:00 ` Peter Zijlstra [this message]
2010-05-25 10:05 ` Piotr Hosowicz
2010-05-25 10:29 ` Piotr Hosowicz
2010-05-25 14:13 ` Piotr Hosowicz
2010-05-25 14:34 ` Piotr Hosowicz
2010-05-25 14:36 ` Peter Zijlstra
2010-05-25 14:48 ` Piotr Hosowicz
2010-05-25 16:15 ` Peter Zijlstra
2010-05-25 16:47 ` Piotr Hosowicz
2010-05-26 2:06 ` Piotr Hosowicz
2010-05-26 2:51 ` Piotr Hosowicz
2010-05-25 18:07 ` Divyesh Shah
2010-05-25 18:15 ` Piotr Hosowicz
2010-05-25 21:35 ` Peter Zijlstra
2010-05-26 23:02 ` Andrew Morton
2010-05-27 6:46 ` Peter Zijlstra
2010-05-27 6:51 ` Andrew Morton
[not found] ` <1274945751.27810.3765.camel@twins>
[not found] ` <20100527113340.d4afb8fc.akpm@linux-foundation.org>
2010-05-28 13:13 ` [PATCH] sched_clock: Provide local_clock() and improve documentation Peter Zijlstra
2010-05-28 13:42 ` Johannes Stezenbach
2010-05-28 15:08 ` Peter Zijlstra
2010-05-28 14:15 ` Piotr Hosowicz
2010-05-28 14:22 ` Piotr Hosowicz
2010-05-28 18:11 ` Chad Talbott
2010-05-28 18:22 ` Peter Zijlstra
2010-06-09 10:13 ` [tip:sched/core] sched_clock: Add local_clock() API " tip-bot for Peter Zijlstra
2010-06-01 6:41 ` BUG: using smp_processor_id() in preemptible [00000000] code: icedove-bin/5449 Ingo Molnar
2010-06-01 6:47 ` Jens Axboe
2010-06-01 6:55 ` Ingo Molnar
2010-06-01 7:53 ` Jens Axboe
2010-06-12 1:54 ` Divyesh Shah
2010-06-12 9:42 ` Peter Zijlstra
2010-06-02 11:16 ` blkiocg_update_io_add_stats(): INFO: trying to register non-static key Ingo Molnar
2010-06-02 13:04 ` Jens Axboe
2010-06-11 1:33 ` Divyesh Shah
2010-06-11 7:15 ` Peter Zijlstra
2010-06-11 8:34 ` Jens Axboe
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