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Message-ID: <20071001033605.GA11497@redhat.com> Date: Sun, 30 Sep 2007 23:36:05 -0400 From: Dave Jones <davej@...hat.com> To: Soeren Sandmann <sandmann@...mi.au.dk> Cc: linux-kernel@...r.kernel.org Subject: Re: [PATCH] Add ability to dump mapped pages with /proc/sys/vm/drop_caches On Sun, Sep 30, 2007 at 08:03:51PM +0200, Soeren Sandmann wrote: > This patch adds the ability to drop mapped pages with > /proc/sys/vm/drop_caches. This is useful to get repeatable > measurements of startup time for applications. > > Without it, pages that are mapped in already-running applications will > not get dropped, so the time measured will not be a true cold-cache > time. > > Rik pointed out that "be_atomic" is a bit pointless since there is a > race on SMP anyway where pages can be added. However, it is there in > the existing code, so I added it for the new code as well. Does anyone > know why it's there? this cset added it (and has a pretty explanatory commit msg) Dave commit fc9a07e7bf1a76e710f5df017abb07628db1781d Author: Andrew Morton <akpm@...ux-foundation.org> Date: Sun Jul 15 23:38:14 2007 -0700 invalidate_mapping_pages(): add cond_resched invalidate_mapping_pages() can sometimes take a long time (millions of pages to free). Long enough for the softlockup detector to trigger. We used to have a cond_resched() in there but I took it out because the drop_caches code calls invalidate_mapping_pages() under inode_lock. The patch adds a nasty flag and puts the cond_resched() back. -- http://www.codemonkey.org.uk - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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