From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:57110 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725916AbeLFTig (ORCPT ); Thu, 6 Dec 2018 14:38:36 -0500 From: Jeff Moyer To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, hch@lst.de Subject: Re: [PATCH 08/26] aio: don't zero entire aio_kiocb aio_get_req() References: <20181204233729.26776-1-axboe@kernel.dk> <20181204233729.26776-9-axboe@kernel.dk> <99b52953-091d-007c-43aa-41198b0ed747@kernel.dk> Date: Thu, 06 Dec 2018 14:38:35 -0500 In-Reply-To: <99b52953-091d-007c-43aa-41198b0ed747@kernel.dk> (Jens Axboe's message of "Thu, 6 Dec 2018 12:28:37 -0700") Message-ID: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Jens Axboe writes: > On 12/6/18 12:27 PM, Jeff Moyer wrote: >> Jens Axboe writes: >> >>> It's 192 bytes, fairly substantial. Most items don't need to be cleared, >>> especially not upfront. Clear the ones we do need to clear, and leave >>> the other ones for setup when the iocb is prepared and submitted. >> >> What performance gains do you see from this? > > Before this, I had 1% in memset doing high IOPS. With it, that's gone. > 1% is a lot, when you have just one thread doing everything from submission > to completion. I'm used to customers complaining about fractions of a percent, so I get it. :-) I just wanted to know we had some measurable impact, as I've seen bugs crop up from code like this in the past. Thanks! Jeff