From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752868AbaGWERj (ORCPT ); Wed, 23 Jul 2014 00:17:39 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:35929 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751207AbaGWERi (ORCPT ); Wed, 23 Jul 2014 00:17:38 -0400 X-IronPort-AV: E=Sophos;i="5.00,931,1396972800"; d="scan'208";a="33664185" Message-ID: <53CF3486.7030902@cn.fujitsu.com> Date: Wed, 23 Jul 2014 12:05:26 +0800 From: Gu Zheng User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20110930 Thunderbird/7.0.1 MIME-Version: 1.0 To: Jeff Moyer CC: , , , , Subject: Re: [PATCH 4/4] aio: use iovec array rather than the single one References: <1405996804-8262-1-git-send-email-guz.fnst@cn.fujitsu.com> <1405996804-8262-4-git-send-email-guz.fnst@cn.fujitsu.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.226.100] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jeff, On 07/22/2014 11:20 PM, Jeff Moyer wrote: > Gu Zheng writes: > >> use an iovec array rather than the single one, so that we can avoid >> to alloc more iovecs buffer in small(< 8) PREADV/PWRITEV cases. > > I did some basic functional testing of this change and the change in > patch 1/4. That testing included using aio-stress to drive queue depths > of 7, 8 and 9, and verify that it didn't fall over. I also ran xfstests > './check -g aio', and libaio's 'make partcheck'. > > The change looks good to me, and passed testing, so: > > Reviewed-by: Jeff Moyer Thanks for your review and test. > > However, I still would like some comment on the reasoning behind it, and > whether there is some measurable performance advantage for some > workload. Additionally, it would be nice if that comment made its way > into the commit message. I'll add more useful info, and send it out later. Thanks, Gu > > Cheers, > Jeff > >> >> Signed-off-by: Gu Zheng >> --- >> fs/aio.c | 10 +++++----- >> 1 files changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/fs/aio.c b/fs/aio.c >> index 0cd0479..ef21efe 100644 >> --- a/fs/aio.c >> +++ b/fs/aio.c >> @@ -1260,12 +1260,12 @@ static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb, >> if (compat) >> ret = compat_rw_copy_check_uvector(rw, >> (struct compat_iovec __user *)buf, >> - *nr_segs, 1, *iovec, iovec); >> + *nr_segs, UIO_FASTIOV, *iovec, iovec); >> else >> #endif >> ret = rw_copy_check_uvector(rw, >> (struct iovec __user *)buf, >> - *nr_segs, 1, *iovec, iovec); >> + *nr_segs, UIO_FASTIOV, *iovec, iovec); >> if (ret < 0) >> return ret; >> >> @@ -1302,7 +1302,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode, >> fmode_t mode; >> aio_rw_op *rw_op; >> rw_iter_op *iter_op; >> - struct iovec inline_vec, *iovec = &inline_vec; >> + struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; >> struct iov_iter iter; >> >> switch (opcode) { >> @@ -1337,7 +1337,7 @@ rw_common: >> if (!ret) >> ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes); >> if (ret < 0) { >> - if (iovec != &inline_vec) >> + if (iovec != inline_vecs) >> kfree(iovec); >> return ret; >> } >> @@ -1384,7 +1384,7 @@ rw_common: >> return -EINVAL; >> } >> >> - if (iovec != &inline_vec) >> + if (iovec != inline_vecs) >> kfree(iovec); >> >> if (ret != -EIOCBQUEUED) { > . >