linux-kernel - Re: [PATCH v2 2/2] task_mmu: Add user-space support for resetting mm->hiwater

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Message-ID: <20150107172452.GA7922@node.dhcp.inet.fi>
Date:	Wed, 7 Jan 2015 19:24:52 +0200
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Petr Cermak <petrcermak@...omium.org>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Primiano Tucci <primiano@...omium.org>,
	Hugh Dickins <hughd@...gle.com>
Subject: Re: [PATCH v2 2/2] task_mmu: Add user-space support for resetting
 mm->hiwater_rss (peak RSS)

On Wed, Jan 07, 2015 at 05:06:54PM +0000, Petr Cermak wrote:
> Peak resident size of a process can be reset by writing "5" to
> /proc/pid/clear_refs. The driving use-case for this would be getting the
> peak RSS value, which can be retrieved from the VmHWM field in
> /proc/pid/status, per benchmark iteration or test scenario.

And how it's not an ABI break?

We have never-lowering VmHWM for 9+ years. How can you know that nobody
expects this behaviour?

And why do you reset hiwater_rss, but not hiwater_vm?

-- 
 Kirill A. Shutemov
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