From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34441) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VoFak-0000wc-HJ for qemu-devel@nongnu.org; Wed, 04 Dec 2013 11:46:32 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VoFae-0003sf-Ti for qemu-devel@nongnu.org; Wed, 04 Dec 2013 11:46:26 -0500 Received: from mx.ipv6.kamp.de ([2a02:248:0:51::16]:43380 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VoFae-0003sW-JA for qemu-devel@nongnu.org; Wed, 04 Dec 2013 11:46:20 -0500 Message-ID: <529F5C56.20906@kamp.de> Date: Wed, 04 Dec 2013 17:46:14 +0100 From: Peter Lieven MIME-Version: 1.0 References: <1385546829-3839-1-git-send-email-pl@kamp.de> <1385546829-3839-9-git-send-email-pl@kamp.de> <20131204164349.GE27759@stefanha-thinkpad.redhat.com> In-Reply-To: <20131204164349.GE27759@stefanha-thinkpad.redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCHv3 1.8 8/9] qemu-img: increase min_sparse to 128 sectors (64kb) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: kwolf@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com Am 04.12.2013 17:43, schrieb Stefan Hajnoczi: > On Wed, Nov 27, 2013 at 11:07:08AM +0100, Peter Lieven wrote: >> Suggested-by: Paolo Bonzini >> Reviewed-by: Paolo Bonzini >> Signed-off-by: Peter Lieven >> --- >> qemu-img.c | 4 ++-- >> qemu-img.texi | 2 +- >> 2 files changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/qemu-img.c b/qemu-img.c >> index 9bb1f6f..8b5f3da 100644 >> --- a/qemu-img.c >> +++ b/qemu-img.c >> @@ -100,7 +100,7 @@ static void help(void) >> " '-h' with or without a command shows this help and lists the supported formats\n" >> " '-p' show progress of command (only certain commands)\n" >> " '-q' use Quiet mode - do not print any output (except errors)\n" >> - " '-S' indicates the consecutive number of bytes (defaults to 4k) that must\n" >> + " '-S' indicates the consecutive number of bytes (defaults to 64k) that must\n" >> " contain only zeros for qemu-img to create a sparse image during\n" >> " conversion. If the number of bytes is 0, the source will not be scanned for\n" >> " unallocated or zero sectors, and the destination image will always be\n" >> @@ -1141,7 +1141,7 @@ static int img_convert(int argc, char **argv) >> QEMUOptionParameter *out_baseimg_param; >> char *options = NULL; >> const char *snapshot_name = NULL; >> - int min_sparse = 8; /* Need at least 4k of zeros for sparse detection */ >> + int min_sparse = 128; /* Need at least 64k of zeros for sparse detection */ >> bool quiet = false; >> Error *local_err = NULL; > I guess a sane size would be cluster size. For a raw file 4 KB is > reasonable since that's the file system block size. in case of iscsi the cluster size could be much too high as for example my storage has a cluster_size of 15MB. > > Is it necessary to increase to 64 KB here? No, its indepent of the rest. Paolo suggested to increase it and I can confirm that for my usage case its faster than 4K. I would drop this patch for now. Peter