From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45252) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y5sz8-0002sz-0w for qemu-devel@nongnu.org; Tue, 30 Dec 2014 04:21:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Y5sz4-00041x-K0 for qemu-devel@nongnu.org; Tue, 30 Dec 2014 04:21:01 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:6567 helo=relay.sw.ru) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y5sz3-0003xV-KR for qemu-devel@nongnu.org; Tue, 30 Dec 2014 04:20:58 -0500 From: "Denis V. Lunev" Date: Tue, 30 Dec 2014 12:20:42 +0300 Message-Id: <1419931250-19259-1-git-send-email-den@openvz.org> Subject: [Qemu-devel] [PATCH v3 0/8] eliminate data write in bdrv_write_zeroes on Linux in raw-posix.c List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , "Denis V. Lunev" , Peter Lieven , qemu-devel@nongnu.org, Stefan Hajnoczi These patches eliminate data writes completely on Linux if fallocate FALLOC_FL_ZERO_RANGE or FALLOC_FL_PUNCH_HOLE are supported on underlying filesystem. I have performed several tests with non-aligned fallocate calls and in all cases (with non-aligned fallocates) Linux performs fine, i.e. areas are zeroed correctly. Checks were made on Linux 3.16.0-28-generic #38-Ubuntu SMP This should seriously increase performance in some special cases. Changes from v2: - added Peter Lieven to CC - added CONFIG_FALLOCATE check to call do_fallocate in patch 7 - dropped patch 1 as NACK-ed - added processing of very large data areas in bdrv_co_write_zeroes (new patch 1) - set bl.max_write_zeroes to INT_MAX in raw-posix.c for regular files (new patch 8) Signed-off-by: Denis V. Lunev CC: Kevin Wolf CC: Stefan Hajnoczi CC: Peter Lieven