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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: kosaki.motohiro@jp.fujitsu.com, Rik van Riel <riel@redhat.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	lee.shermerhorn@hp.com,
	Lee Schermerhorn <lee.schermerhorn@hp.com>
Subject: Re: [patch 02/20] make the inode i_mmap_lock a reader/writer lock
Date: Wed, 19 Dec 2007 13:09:10 +0900	[thread overview]
Message-ID: <20071219124513.9853.KOSAKI.MOTOHIRO@jp.fujitsu.com> (raw)
In-Reply-To: <200712191148.06506.nickpiggin@yahoo.com.au>

Hi

> > rmap:  try_to_unmap_file() required new cond_resched_rwlock().
> > To reduce code duplication, I recast cond_resched_lock() as a
> > [static inline] wrapper around reworked cond_sched_lock() =>
> > __cond_resched_lock(void *lock, int type).
> > New cond_resched_rwlock() implemented as another wrapper.
> 
> Reader/writer locks really suck in terms of fairness and starvation,
> especially when the read-side is common and frequent. (also, single
> threaded performance of the read-side is worse).

Agreed.

rwlock got bad performance some case. (especially on many cpu machine)

if many cpu grab read-lock on and off on many cpu system.
then at least 1 cpu always grab read lock and the cpu of waiting write-lock 
never get lock.

threrefore, rwlock often make performance weakness of stress.


I want know testcase for this patch and run it.
Do you have it?


/kosaki



  reply	other threads:[~2007-12-19  4:09 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-12-18 21:15 [patch 00/20] VM pageout scalability improvements Rik van Riel
2007-12-18 21:15 ` [patch 01/20] convert anon_vma list lock a read/write lock Rik van Riel
2007-12-20  7:07   ` Christoph Lameter
2007-12-18 21:15 ` [patch 02/20] make the inode i_mmap_lock a reader/writer lock Rik van Riel
2007-12-19  0:48   ` Nick Piggin
2007-12-19  4:09     ` KOSAKI Motohiro [this message]
2007-12-19 15:52     ` Lee Schermerhorn
2007-12-19 16:31       ` Rik van Riel
2007-12-19 16:53         ` Lee Schermerhorn
2007-12-19 19:28           ` Peter Zijlstra
2007-12-19 23:40             ` Nick Piggin
2007-12-20  7:04               ` Christoph Lameter
2007-12-20  7:59                 ` Nick Piggin
2008-01-02 23:35                   ` Mike Travis
2008-01-03  6:07                     ` Nick Piggin
2008-01-03  8:55                       ` Ingo Molnar
2008-01-07  9:01                         ` Nick Piggin
2007-12-18 21:15 ` [patch 03/20] move isolate_lru_page() to vmscan.c Rik van Riel
2007-12-20  7:08   ` Christoph Lameter
2007-12-18 21:15 ` [patch 04/20] free swap space on swap-in/activation Rik van Riel
2007-12-18 21:15 ` [patch 05/20] define page_file_cache() function Rik van Riel
2007-12-18 21:15 ` [patch 06/20] debugging checks for page_file_cache() Rik van Riel
2007-12-18 21:15 ` [patch 07/20] Use an indexed array for LRU variables Rik van Riel
2007-12-18 21:15 ` [patch 08/20] split LRU lists into anon & file sets Rik van Riel
2007-12-18 21:15 ` [patch 09/20] split anon & file LRUs for memcontrol code Rik van Riel
2007-12-18 21:15 ` [patch 10/20] SEQ replacement for anonymous pages Rik van Riel
2007-12-19  5:17   ` KOSAKI Motohiro
2007-12-19 13:40     ` Rik van Riel
2007-12-20  2:04       ` KOSAKI Motohiro
2007-12-18 21:15 ` [patch 11/20] add newly swapped in pages to the inactive list Rik van Riel
2007-12-18 21:15 ` [patch 12/20] No Reclaim LRU Infrastructure Rik van Riel
2007-12-18 21:15 ` [patch 13/20] Non-reclaimable page statistics Rik van Riel
2007-12-18 21:15 ` [patch 14/20] Scan noreclaim list for reclaimable pages Rik van Riel
2007-12-18 21:15 ` [patch 15/20] ramfs pages are non-reclaimable Rik van Riel
2007-12-18 21:15 ` [patch 16/20] SHM_LOCKED pages are nonreclaimable Rik van Riel
2007-12-18 21:15 ` [patch 17/20] non-reclaimable mlocked pages Rik van Riel
2007-12-19  0:56   ` Nick Piggin
2007-12-19 13:45     ` Rik van Riel
2007-12-19 14:24       ` Peter Zijlstra
2007-12-19 14:53         ` Rik van Riel
2007-12-19 16:08           ` Lee Schermerhorn
2007-12-19 16:04       ` Lee Schermerhorn
2007-12-20 20:56         ` Rik van Riel
2007-12-21 10:52           ` Nick Piggin
2007-12-21 14:17             ` Rik van Riel
2007-12-23 12:22               ` Nick Piggin
2007-12-24  1:00                 ` Rik van Riel
2007-12-19 23:34       ` Nick Piggin
2007-12-20  7:19     ` Christoph Lameter
2007-12-20 15:33       ` Rik van Riel
2007-12-21 17:13         ` Lee Schermerhorn
2007-12-18 21:15 ` [patch 18/20] mlock vma pages under mmap_sem held for read Rik van Riel
2007-12-18 21:15 ` [patch 19/20] handle mlocked pages during map/unmap and truncate Rik van Riel
2007-12-18 21:15 ` [patch 20/20] account mlocked pages Rik van Riel
2007-12-22 20:27 ` [patch 00/20] VM pageout scalability improvements Balbir Singh
2007-12-23  0:21   ` Rik van Riel
2007-12-23 22:59     ` Balbir Singh
2007-12-24  1:11       ` Rik van Riel
2007-12-28  3:20         ` Matt Mackall

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