From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37841) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wi3k6-000844-Nk for qemu-devel@nongnu.org; Wed, 07 May 2014 11:26:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wi3k1-00074Y-0V for qemu-devel@nongnu.org; Wed, 07 May 2014 11:26:46 -0400 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:60200 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wi3k0-00074O-M0 for qemu-devel@nongnu.org; Wed, 07 May 2014 11:26:40 -0400 Message-ID: <536A50A2.1020008@kamp.de> Date: Wed, 07 May 2014 17:26:26 +0200 From: Peter Lieven MIME-Version: 1.0 References: <1399422203-5861-1-git-send-email-pl@kamp.de> <53699FE4.5030004@redhat.com> <536A42B0.1070307@kamp.de> <20140507151938.GG4045@noname.str.redhat.com> In-Reply-To: <20140507151938.GG4045@noname.str.redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCHv3] block: optimize zero writes with bdrv_write_zeroes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: famz@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com, pbonzini@redhat.com On 07.05.2014 17:19, Kevin Wolf wrote: > Am 07.05.2014 um 16:26 hat Peter Lieven geschrieben: >> On 07.05.2014 04:52, Eric Blake wrote: >>> On 05/06/2014 06:23 PM, Peter Lieven wrote: >>>> this patch tries to optimize zero write requests >>>> by automatically using bdrv_write_zeroes if it is >>>> supported by the format. >>>> >>>> This significantly speeds up file system initialization and >>>> should speed zero write test used to test backend storage >>>> performance. >>>> >>>> Signed-off-by: Peter Lieven >>>> --- >>>> v2->v3: - moved parameter parsing to blockdev_init >>>> - added per device detect_zeroes status to >>>> hmp (info block -v) and qmp (query-block) [Eric] >>>> - added support to enable detect-zeroes also >>>> for hot added devices [Eric] >>>> - added missing entry to qemu_common_drive_opts >>>> - fixed description of qemu_iovec_is_zero [Fam] >>>> >>>> +static BdrvDetectZeroes parse_detect_zeroes(const char *buf, Error **errp) >>>> +{ >>>> + if (!buf || !strcmp(buf, "off")) { >>>> + return BDRV_DETECT_ZEROES_OFF; >>>> + } else if (!strcmp(buf, "on")) { >>>> + return BDRV_DETECT_ZEROES_ON; >>>> + } else if (!strcmp(buf, "unmap")) { >>>> + return BDRV_DETECT_ZEROES_UNMAP; >>>> + } else { >>>> + error_setg(errp, "invalid value for detect-zeroes: %s", >>>> + buf); >>>> + } >>>> + return BDRV_DETECT_ZEROES_OFF; >>>> +} >>> Isn't there QAPI generated code that you can use instead of open-coding >>> this conversion between string and enum values? >> Actually I have no idea. As you pointed out in the qapi patch I sent >> it was quite hard for me to crawl through the whole stuff as one who is not >> familiar with it. Can somebody advise here? Anyhow, I wonder >> how this would work since qapi doesn't know the C Macros. > QAPI does generate C enums, so you should take whatever identifier it > uses instead of defining your own macros. You may need to include > qapi-types.h for this. It also creates a *_lookup array that maps enum > IDs to strings. Ah, cool stuff, thank you. I found the enum and the lookup array, but is there also a function that maps a string to an enum ID? Peter > > Kevin -- Mit freundlichen Grüßen Peter Lieven ........................................................... KAMP Netzwerkdienste GmbH Vestische Str. 89-91 | 46117 Oberhausen Tel: +49 (0) 208.89 402-50 | Fax: +49 (0) 208.89 402-40 pl@kamp.de | http://www.kamp.de Geschäftsführer: Heiner Lante | Michael Lante Amtsgericht Duisburg | HRB Nr. 12154 USt-Id-Nr.: DE 120607556 ...........................................................