From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756796AbbA2GGL (ORCPT ); Thu, 29 Jan 2015 01:06:11 -0500 Received: from mail-pa0-f53.google.com ([209.85.220.53]:57440 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752878AbbA2GGH (ORCPT ); Thu, 29 Jan 2015 01:06:07 -0500 Date: Thu, 29 Jan 2015 15:06:04 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , Sergey Senozhatsky , Andrew Morton , "linux-kernel@vger.kernel.org" , Linux-MM , Nitin Gupta , Jerome Marchand , Ganesh Mahendran Subject: Re: [PATCH v1 2/2] zram: remove init_lock in zram_make_request Message-ID: <20150129060604.GC2555@swordfish> References: <1422432945-6764-1-git-send-email-minchan@kernel.org> <1422432945-6764-2-git-send-email-minchan@kernel.org> <20150128145651.GB965@swordfish> <20150128233343.GC4706@blaptop> <20150129020139.GB9672@blaptop> <20150129022241.GA2555@swordfish> <20150129052827.GB25462@blaptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150129052827.GB25462@blaptop> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (01/29/15 14:28), Minchan Kim wrote: > > I'm still concerned about performance numbers that I see on my x86_64. > > it's not always, but mostly slower. I'll give it another try (disable > > lockdep, etc.), but if we lose 10% on average then, sorry, I'm not so > > positive about srcu change and will tend to vote for your initial commit > > that simply moved meta free() out of init_lock and left locking as is > > (lockdep warning would have been helpful there, because otherwise it > > just looked like we change code w/o any reason). > > > > what do you thunk? > > Surely I agreee with you. If it suffers from 10% performance regression, > it's absolutely no go. > > However, I believe it should be no loss because that's one of the reason > from RCU birth which should be really win in read-side lock path compared > to other locking. > > Please test it with dd or something for block-based test for removing > noise from FS. I also will test it to confirm that with real machine. > do you test with a single dd thread/process? just dd if=foo of=bar -c... or you start N `dd &' processes? for a single writer there should be no difference, no doubt. I'm more interested in multi-writer/multi-reader/mixed use cases. the options that I use are: iozone -t 3 -R -r 16K -s 60M -I +Z and -I is: -I Use VxFS VX_DIRECT, O_DIRECT,or O_DIRECTIO for all file operations with O_DIRECT I don't think there is a lot of noise, but I'll try to use different benchmarks a bit later. -ss