From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <444F8714.9060808@yahoo.com.au> Date: Thu, 27 Apr 2006 00:43:32 +1000 From: Nick Piggin MIME-Version: 1.0 Subject: Re: Lockless page cache test results References: <20060426135310.GB5083@suse.de> In-Reply-To: <20060426135310.GB5083@suse.de> 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: linux-kernel@vger.kernel.org, Nick Piggin , Andrew Morton , linux-mm@kvack.org List-ID: Jens Axboe wrote: > Hi, > > Running a splice benchmark on a 4-way IPF box, I decided to give the > lockless page cache patches from Nick a spin. I've attached the results > as a png, it pretty much speaks for itself. > > The test in question splices a 1GiB file to a pipe and then splices that > to some output. Normally that output would be something interesting, in > this case it's simply /dev/null. So it tests the input side of things > only, which is what I wanted to do here. To get adequate runtime, the > operation is repeated a number of times (120 in this example). The > benchmark does that number of loops with 1, 2, 3, and 4 clients each > pinned to a private CPU. The pinning is mainly done for more stable > results. Thanks Jens! It's interesting, single threaded performance is down a little. Is this significant? In some other results you showed me with 3 splices each running on their own file (ie. no tree_lock contention), lockless looked slightly faster on the same machine. In my microbenchmarks, single threaded lockless is quite a bit faster than vanilla on both P4 and G5. It could well be that the speculative get_page operation is naturally a bit slower on Itanium CPUs -- there is a different mix of barriers, reads, writes, etc. If only someone gave me an IPF system... ;) As you said, it would be nice to see how this goes when the other end are 4 gigabit pipes or so... And then things like specweb and file serving workloads. 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