From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <44507AA9.2010005@yahoo.com.au> Date: Thu, 27 Apr 2006 18:02:49 +1000 From: Nick Piggin MIME-Version: 1.0 Subject: Re: Lockless page cache test results References: <20060426135310.GB5083@suse.de> <20060426095511.0cc7a3f9.akpm@osdl.org> <20060426174235.GC5002@suse.de> <20060426111054.2b4f1736.akpm@osdl.org> <20060426191557.GA9211@suse.de> <20060426131200.516cbabc.akpm@osdl.org> <20060427074533.GJ9211@suse.de> <4450796A.2030908@yahoo.com.au> In-Reply-To: <4450796A.2030908@yahoo.com.au> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Jens Axboe Cc: Andrew Morton , torvalds@osdl.org, linux-kernel@vger.kernel.org, npiggin@suse.de, linux-mm@kvack.org List-ID: Nick Piggin wrote: > Jens Axboe wrote: > >> Things look pretty bad for the lockless kernel though, Nick any idea >> what is going on there? The splice change is pretty simple, see the top >> three patches here: > > > Could just be the use of spin lock instead of read lock. > > I don't think it would be hard to convert find_get_pages_contig > to be lockless. > > Patched vanilla numbers look nicer, but I'm curious as to why > __do_page_cache was so bad before, if the file was in cache. > Presumably it should not more than double tree_lock acquisition... > it isn't getting called multiple times for each page, is it? Hmm, what's more, find_get_pages_contig shouldn't result in any fewer tree_lock acquires than the open coded thing there now (for the densely populated pagecache case). -- 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