From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Ravikiran G Thirumalai <kiran@scalex86.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andi Kleen <ak@suse.de>, Andrew Morton <akpm@osdl.org>,
"Shai Fultheim (Shai@scalex86.org)" <shai@scalex86.org>,
pravin b shelar <pravin.shelar@calsoftinc.com>
Subject: Re: High lock spin time for zone->lru_lock under extreme conditions
Date: Sat, 13 Jan 2007 18:53:44 +1100 [thread overview]
Message-ID: <45A89008.2030408@yahoo.com.au> (raw)
In-Reply-To: <20070113073643.GA4234@localhost.localdomain>
Ravikiran G Thirumalai wrote:
> On Sat, Jan 13, 2007 at 03:39:45PM +1100, Nick Piggin wrote:
>>What is the "CS time"?
>
>
> Critical Section :). This is the maximal time interval I measured from
> t2 above to the time point we release the spin lock. This is the hold
> time I guess.
>
>
>>It would be interesting to know how long the maximal lru_lock *hold* time
>>is,
>>which could give us a better indication of whether it is a hardware problem.
>>
>>For example, if the maximum hold time is 10ms, that it might indicate a
>>hardware fairness problem.
>
>
> The maximal hold time was about 3s.
Well then it doesn't seem very surprising that this could cause a 30s wait
time for one CPU in a 16 core system, regardless of fairness.
I guess most of the contention, and the lock hold times are coming from
vmscan? Do you know exactly which critical sections are the culprits?
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Ravikiran G Thirumalai <kiran@scalex86.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andi Kleen <ak@suse.de>, Andrew Morton <akpm@osdl.org>,
"Shai Fultheim (Shai@scalex86.org)" <shai@scalex86.org>,
pravin b shelar <pravin.shelar@calsoftinc.com>
Subject: Re: High lock spin time for zone->lru_lock under extreme conditions
Date: Sat, 13 Jan 2007 18:53:44 +1100 [thread overview]
Message-ID: <45A89008.2030408@yahoo.com.au> (raw)
In-Reply-To: <20070113073643.GA4234@localhost.localdomain>
Ravikiran G Thirumalai wrote:
> On Sat, Jan 13, 2007 at 03:39:45PM +1100, Nick Piggin wrote:
>>What is the "CS time"?
>
>
> Critical Section :). This is the maximal time interval I measured from
> t2 above to the time point we release the spin lock. This is the hold
> time I guess.
>
>
>>It would be interesting to know how long the maximal lru_lock *hold* time
>>is,
>>which could give us a better indication of whether it is a hardware problem.
>>
>>For example, if the maximum hold time is 10ms, that it might indicate a
>>hardware fairness problem.
>
>
> The maximal hold time was about 3s.
Well then it doesn't seem very surprising that this could cause a 30s wait
time for one CPU in a 16 core system, regardless of fairness.
I guess most of the contention, and the lock hold times are coming from
vmscan? Do you know exactly which critical sections are the culprits?
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
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next prev parent reply other threads:[~2007-01-13 7:55 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-12 16:01 High lock spin time for zone->lru_lock under extreme conditions Ravikiran G Thirumalai
2007-01-12 16:01 ` Ravikiran G Thirumalai
2007-01-12 17:03 ` Peter Zijlstra
2007-01-12 17:03 ` Peter Zijlstra
2007-01-12 19:46 ` Christoph Lameter
2007-01-12 19:46 ` Christoph Lameter
2007-01-12 21:25 ` Andrew Morton
2007-01-12 21:25 ` Andrew Morton
2007-01-12 21:40 ` Ravikiran G Thirumalai
2007-01-12 21:40 ` Ravikiran G Thirumalai
2007-01-12 21:45 ` Christoph Lameter
2007-01-12 21:45 ` Christoph Lameter
2007-01-13 1:00 ` Ravikiran G Thirumalai
2007-01-13 1:00 ` Ravikiran G Thirumalai
2007-01-13 1:11 ` Andrew Morton
2007-01-13 1:11 ` Andrew Morton
2007-01-13 7:42 ` Ravikiran G Thirumalai
2007-01-13 7:42 ` Ravikiran G Thirumalai
2007-01-13 4:39 ` Nick Piggin
2007-01-13 4:39 ` Nick Piggin
2007-01-13 7:36 ` Ravikiran G Thirumalai
2007-01-13 7:36 ` Ravikiran G Thirumalai
2007-01-13 7:53 ` Nick Piggin [this message]
2007-01-13 7:53 ` Nick Piggin
2007-01-13 8:00 ` Andrew Morton
2007-01-13 8:00 ` Andrew Morton
2007-01-13 19:53 ` Ravikiran G Thirumalai
2007-01-13 19:53 ` Ravikiran G Thirumalai
2007-01-13 21:20 ` Andrew Morton
2007-01-13 21:20 ` Andrew Morton
2007-01-16 2:56 ` Ravikiran G Thirumalai
2007-01-16 2:56 ` Ravikiran G Thirumalai
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