linux-kernel - Re: [PATCH 2.6.20-rc1 00/10] Kernel memory leak detector 0.13

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Message-ID: <20061217132840.GA15892@elte.hu>
Date:	Sun, 17 Dec 2006 14:28:40 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Catalin Marinas <catalin.marinas@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2.6.20-rc1 00/10] Kernel memory leak detector 0.13


* Catalin Marinas <catalin.marinas@...il.com> wrote:

> On 17/12/06, Ingo Molnar <mingo@...e.hu> wrote:
> >one more thing: after bootup i need to access the /debug/memleak file 
> >twice to get any output from it - is that normal? The first 'cat 
> >/debug/memleak' gives no output (but there's the usual scanning 
> >delay, so memleak does do its work).
> 
> Yes, this is normal. Especially on SMP, I get some transient reports, 
> probably caused by pointers hold in registers (even more visible on 
> ARM due to the bigger number of registers per CPU). Reporting a leak 
> only if it was seen at least once before greatly reduces the false 
> positives (this is configurable as well but I'll drop the 
> configuration option). Without this, you could see that, at every 
> scan, the reported pointers are different.
> 
> Some people testing kmemleak used to read the /debug/memleak file 
> periodically from a script and this wasn't noticeable. It would be 
> even better if, as you suggested, I schedule a periodic memory 
> scanning.

yeah. You could also use the allocation timestamp to exclude too young 
entries. (if something really leaked then it will be a leak in 10 
minutes too)

	Ingo
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