From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40125) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cbVrE-0006Gt-Tq for qemu-devel@nongnu.org; Wed, 08 Feb 2017 12:16:41 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cbVrA-0000Xd-PJ for qemu-devel@nongnu.org; Wed, 08 Feb 2017 12:16:40 -0500 Date: Wed, 8 Feb 2017 17:16:33 +0000 From: Stephane Chazelas Message-ID: <20170208171633.GC19518@chaz.gmail.com> References: <20170202123045.GA24714@chaz.gmail.com> <20170208140646.GA19518@chaz.gmail.com> <11bfda2a-7799-a5d5-4ba0-37b2b9dd92f6@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <11bfda2a-7799-a5d5-4ba0-37b2b9dd92f6@redhat.com> Subject: Re: [Qemu-devel] [qcow2] how to avoid qemu doing lseek(SEEK_DATA/SEEK_HOLE)? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz Cc: Kevin Wolf , qemu-devel@nongnu.org, Qemu-block 2017-02-08 15:27:11 +0100, Max Reitz: [...] > A bit of a stupid question, but: How is your performance when using > detect-zeroes=off? [...] I did try that. See: } Note that passing detect-zeroes=off or detect-zeroes=unmap (with } discard) doesn't help (even though FALLOC_FL_PUNCH_HOLE is } supported on ZFS on Linux). In my original message. It makes no difference, I still see those lseek()s being done. -- Stephane