From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43429) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fTSAi-0008Ux-WC for qemu-devel@nongnu.org; Thu, 14 Jun 2018 09:20:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fTSAe-00035k-2W for qemu-devel@nongnu.org; Thu, 14 Jun 2018 09:20:16 -0400 References: <20180608192027.284601-1-vsementsov@virtuozzo.com> <20180608192027.284601-4-vsementsov@virtuozzo.com> <20180614131652.GF8564@localhost.localdomain> From: "Denis V. Lunev" Message-ID: Date: Thu, 14 Jun 2018 16:19:52 +0300 MIME-Version: 1.0 In-Reply-To: <20180614131652.GF8564@localhost.localdomain> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Subject: Re: [Qemu-devel] [PATCH 3/3] qcow2: add compress threads List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf , Vladimir Sementsov-Ogievskiy Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, mreitz@redhat.com, stefanha@gmail.com, pl@kamp.de On 06/14/2018 04:16 PM, Kevin Wolf wrote: > Am 08.06.2018 um 21:20 hat Vladimir Sementsov-Ogievskiy geschrieben: >> Do data compression in separate threads. This significantly improve >> performance for qemu-img convert with -W (allow async writes) and -c >> (compressed) options. >> >> Signed-off-by: Vladimir Sementsov-Ogievskiy > Looks correct to me, but why do we introduce a separate > MAX_COMPRESS_THREADS? Can't we simply leave the maximum number of > threads to the thread poll? > > I see that you chose a much smaller number here (4 vs. 64), but is there > actually a good reason for this? > > Kevin yes. In the other case the guest will suffer much more from this increased activity and load on the host. Den