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Date: Tue, 19 May 2009 13:44:19 +0900 (JST) From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> To: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> Cc: kosaki.motohiro@...fujitsu.com, Wu Fengguang <fengguang.wu@...el.com>, Christoph Lameter <cl@...ux-foundation.org>, Andrew Morton <akpm@...ux-foundation.org>, LKML <linux-kernel@...r.kernel.org>, Elladan <elladan@...imo.com>, Nick Piggin <npiggin@...e.de>, Johannes Weiner <hannes@...xchg.org>, Peter Zijlstra <peterz@...radead.org>, Rik van Riel <riel@...hat.com>, "tytso@....edu" <tytso@....edu>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "minchan.kim@...il.com" <minchan.kim@...il.com> Subject: Re: [PATCH 2/3] vmscan: make mapped executable pages the first class citizen > > begin: 2479 2344 9659 210 0 579643 > > end: 284 232010 234142 260 772776 20917184 > > restore: 379 232159 234371 301 774888 20967849 > > > > The numbers show that > > > > - The startup pgmajfault of 2.6.30-rc4-mm is merely 1/3 that of 2.6.29. > > I'd attribute that improvement to the mmap readahead improvements :-) > > > > - The pgmajfault increment during the file copy is 633-630=3 vs 260-210=50. > > That's a huge improvement - which means with the VM_EXEC protection logic, > > active mmap pages is pretty safe even under partially cache hot streaming IO. > > > > - when active:inactive file lru size reaches 1:1, their scan rates is 1:20.8 > > under 10% cache hot IO. (computed with formula Dpgdeactivate:Dpgfree) > > That roughly means the active mmap pages get 20.8 more chances to get > > re-referenced to stay in memory. > > > > - The absolute nr_mapped drops considerably to 1/9 during the big IO, and the > > dropped pages are mostly inactive ones. The patch has almost no impact in > > this aspect, that means it won't unnecessarily increase memory pressure. > > (In contrast, your 20% mmap protection ratio will keep them all, and > > therefore eliminate the extra 41 major faults to restore working set > > of zsh etc.) > > I'm surprised this. > Why your patch don't protect mapped page from streaming io? I guess you use initlevel=5 and use only terminal, right? if so, dropping some graphics component makes sense. > > I strongly hope reproduce myself, please teach me reproduce way. -- 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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