From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: Linux I/O performance in 2.3.99pre References: Reply-To: zlatko@iskon.hr From: Zlatko Calusic Date: 24 May 2000 11:17:30 +0200 In-Reply-To: Andrea Arcangeli's message of "Mon, 22 May 2000 22:08:11 -0700 (PDT)" Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: linux-kernel@vger.rutgers.edu, linux-mm@kvack.org List-ID: Andrea Arcangeli writes: > On 22 May 2000, Zlatko Calusic wrote: > > >Question for Andrea: is it possible to get back to the old speeds with > >tha new elevator code, or is the speed drop unfortunate effect of the > >"non-starvation" logic, and thus can't be cured? > > If you don't mind about I/O scheduling latencies then just use elvtune and > set read/write latency to a big number (for example 1000000) and set the > write-bomb logic value to 128. However in misc usage you care about > responsiveness as well as latency so you probably don't want to disable > the I/O scheduler completly. The write bomb logic defaul value is too > strict probably and we may want to enlarge it to 32 or 64 to allow SCSI > to be more effective. > Yes, you are right. I tested performance with different parameters to elvtune, and it definitely improves rewriting speed if I put bigger numbers. In fact with 1000000/1000000/128 it is back to 2.3.42 results (rewriting speed ~9.2MB/s). While at it, could you explain what are write bomb logic and latency numbers? What do they define? > About the bad VM performance of the latest kernels please try again with > pre9-1 + classzone-28. > I did a test with pre8 + classzone28 (didn't have 9-1 at the moment, but there was only one easily resolvable conflict in vmscan.c). And I must admit that I'm completely satisfied with its behaviour. System is definitely working right AND fast. It reads, writes and swaps with full speed and the system survived all tests I made against it. With classzone patch applied, VM/IO balance/behaviour seems perfect. Too bad the patch is not going to make it to the Linus kernel tree, but hey, there's always a possibility of applying a patch for better performance. Assuming you continue porting the patch to forthcoming kernels, of course (that's to say I tried to port it to the pre9-4 and failed :)). Regards, -- Zlatko -- 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.eu.org/Linux-MM/