From: Rik van Riel <riel@redhat.com>
To: Ying Han <yinghan@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V8] Eliminate task stack trace duplication
Date: Fri, 06 Apr 2012 14:57:45 -0400 [thread overview]
Message-ID: <4F7F3CA9.1030500@redhat.com> (raw)
In-Reply-To: <1333737920-17555-1-git-send-email-yinghan@google.com>
On 04/06/2012 02:45 PM, Ying Han wrote:
> The problem with small dmesg ring buffer like 512k is that only limited number
> of task traces will be logged. Sometimes we lose important information only
> because of too many duplicated stack traces. This problem occurs when dumping
> lots of stacks in a single operation, such as sysrq-T.
>
> This patch tries to reduce the duplication of task stack trace in the dump
> message by hashing the task stack. The hashtable is a 32k pre-allocated buffer
> during bootup. Each time if we find the identical task trace in the task stack,
> we dump only the pid of the task which has the task trace dumped. So it is easy
> to back track to the full stack with the pid.
> Signed-off-by: Ying Han<yinghan@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
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WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Ying Han <yinghan@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V8] Eliminate task stack trace duplication
Date: Fri, 06 Apr 2012 14:57:45 -0400 [thread overview]
Message-ID: <4F7F3CA9.1030500@redhat.com> (raw)
In-Reply-To: <1333737920-17555-1-git-send-email-yinghan@google.com>
On 04/06/2012 02:45 PM, Ying Han wrote:
> The problem with small dmesg ring buffer like 512k is that only limited number
> of task traces will be logged. Sometimes we lose important information only
> because of too many duplicated stack traces. This problem occurs when dumping
> lots of stacks in a single operation, such as sysrq-T.
>
> This patch tries to reduce the duplication of task stack trace in the dump
> message by hashing the task stack. The hashtable is a 32k pre-allocated buffer
> during bootup. Each time if we find the identical task trace in the task stack,
> we dump only the pid of the task which has the task trace dumped. So it is easy
> to back track to the full stack with the pid.
> Signed-off-by: Ying Han<yinghan@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
--
All rights reversed
next prev parent reply other threads:[~2012-04-06 18:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-06 18:45 [PATCH V8] Eliminate task stack trace duplication Ying Han
2012-04-06 18:45 ` Ying Han
2012-04-06 18:57 ` Rik van Riel [this message]
2012-04-06 18:57 ` Rik van Riel
2012-04-26 19:33 ` Ying Han
2012-04-26 19:33 ` Ying Han
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