From: Piotr Hosowicz <piotr@hosowicz.com>
To: Peter Zijlstra <peterz@infradead.org>
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 12:05:44 +0200 [thread overview]
Message-ID: <4BFBA0F8.9090908@example.com> (raw)
In-Reply-To: <1274781655.5882.765.camel@twins>
On 25.05.2010 12:00, Peter Zijlstra wrote:
> 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.
Thanks.
Cheers,
Piotr Hosowicz
--
"Wiedza to władza. Ale niewiedza, niestety, nie oznacza jeszcze
braku władzy." Niels Bohr
NP: Black Stone Cherry - Reverend Wrinkle
NB: 2.6.34-20100524-1752
next prev parent reply other threads:[~2010-05-25 10:05 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
2010-05-25 10:05 ` Piotr Hosowicz [this message]
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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