From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <432A3810.9070600@yahoo.com.au> Date: Fri, 16 Sep 2005 13:12:16 +1000 From: Nick Piggin MIME-Version: 1.0 Subject: Re: New lockless pagecache References: <4317F071.1070403@yahoo.com.au> <4317F50B.6080005@yahoo.com.au> <35f686220509151250e598fda@mail.gmail.com> In-Reply-To: <35f686220509151250e598fda@mail.gmail.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: alokkataria1@gmail.com Cc: Linux Memory Management , linux-kernel List-ID: Alok kataria wrote: > Hi Nick, > > I have collected performance numbers for the lock less page cache > patch on the AIM - IO test. > The performance numbers are collected for 1-100 tasks 1-50 tasks and > 90-100 tasks both for with and without your patch. This was done on > 2.6.13 kernel. > There's definite improvement when the tasks are small i.e ~50-70. But > when the tasks go beyond 80, we see a large performance dip. > I again profiled the 90-100 runs with spinlock's inlined, but couldn't > understand the reason behind the performance difference. > > Please find attached the performance numbers as well as the oprofile logs. > Hi Alok, Thanks very much for doing these numbers. Performance is improved significantly at smaller numbers of tasks, as you say. Unfortunately I can't pinpoint the reason why performance drops at larger numbers. I could assume that the last remaining place that used read_lock_irq for the tree_lock (wait_on_page_writeback_range) got hurt when switching to spinlocks, but that would seem vary unlikely. I'll have to look into it further. Thanks, Nick -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org