From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49389) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YGAxY-0002I6-BV for qemu-devel@nongnu.org; Tue, 27 Jan 2015 13:33:57 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YGAxQ-0004Hc-Oz for qemu-devel@nongnu.org; Tue, 27 Jan 2015 13:33:54 -0500 Received: from mx2.parallels.com ([199.115.105.18]:41158) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YGAxQ-0004HC-K6 for qemu-devel@nongnu.org; Tue, 27 Jan 2015 13:33:48 -0500 Message-ID: <54C7DA03.3030006@openvz.org> Date: Tue, 27 Jan 2015 21:33:39 +0300 From: "Denis V. Lunev" MIME-Version: 1.0 References: <1422366699-17473-1-git-send-email-den@openvz.org> <1422366699-17473-7-git-send-email-den@openvz.org> <54C7D19F.20408@redhat.com> <54C7D6A1.6080500@openvz.org> <54C7D7CC.9090604@redhat.com> In-Reply-To: <54C7D7CC.9090604@redhat.com> Content-Type: text/plain; charset="iso-8859-15"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 6/7] block/raw-posix: call plain fallocate in handle_aiocb_write_zeroes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz Cc: Kevin Wolf , Peter Lieven , Fam Zheng , qemu-devel@nongnu.org, Stefan Hajnoczi On 27/01/15 21:24, Max Reitz wrote: > On 2015-01-27 at 13:19, Denis V. Lunev wrote: >> On 27/01/15 20:57, Max Reitz wrote: >>> On 2015-01-27 at 08:51, Denis V. Lunev wrote: >>>> There is a possibility that we are extending our image and thus >>>> writing >>>> zeroes beyond the end of the file. In this case we do not need to care >>>> about the hole to make sure that there is no data in the file under >>>> this offset (pre-condition to fallocate(0) to work). We could >>>> simply call >>>> fallocate(0). >>>> >>>> This improves the performance of writing zeroes even on really old >>>> platforms which do not have even FALLOC_FL_PUNCH_HOLE. >>>> >>>> Signed-off-by: Denis V. Lunev >>>> CC: Kevin Wolf >>>> CC: Stefan Hajnoczi >>>> CC: Peter Lieven >>>> CC: Fam Zheng >>>> --- >>>> block/raw-posix.c | 10 ++++++++-- >>>> 1 file changed, 8 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/block/raw-posix.c b/block/raw-posix.c >>>> index c039bef..fa05239 100644 >>>> --- a/block/raw-posix.c >>>> +++ b/block/raw-posix.c >>>> @@ -60,7 +60,7 @@ >>>> #define FS_NOCOW_FL 0x00800000 /* Do not cow >>>> file */ >>>> #endif >>>> #endif >>>> -#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) || >>>> defined(CONFIG_FALLOCATE_ZERO_RANGE) >>>> +#ifdef CONFIG_FALLOCATE >>> >>> This change doesn't seem right; CONFIG_FALLOCATE is set if >>> posix_fallocate() is available, not for the Linux-specific >>> fallocate() from linux/falloc.h. >>> >> >> here is a check for fallocate and posix_fallocate in configure script >> >> # check for fallocate >> fallocate=no >> cat > $TMPC << EOF >> #include >> >> int main(void) >> { >> fallocate(0, 0, 0, 0); >> return 0; >> } >> EOF >> if compile_prog "" "" ; then >> fallocate=yes >> fi >> ... >> # check for posix_fallocate >> posix_fallocate=no >> cat > $TMPC << EOF >> #include >> >> int main(void) >> { >> posix_fallocate(0, 0, 0); >> return 0; >> } >> EOF >> if compile_prog "" "" ; then >> posix_fallocate=yes >> fi >> ... >> if test "$fallocate" = "yes" ; then >> echo "CONFIG_FALLOCATE=y" >> $config_host_mak >> fi >> ... >> if test "$posix_fallocate" = "yes" ; then >> echo "CONFIG_POSIX_FALLOCATE=y" >> $config_host_mak >> fi >> >> Thus my check looks correct to me. > > Oh, sorry, I somehow mixed those checks. You're right. > > Very well then; maybe you want to mention this change in the commit > message, though? > > Max > no prob