From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:53769) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1grhwL-0001wm-GL for qemu-devel@nongnu.org; Thu, 07 Feb 2019 06:33:58 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1grhw9-0004bH-C7 for qemu-devel@nongnu.org; Thu, 07 Feb 2019 06:33:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57434) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1grhvy-0004VO-BM for qemu-devel@nongnu.org; Thu, 07 Feb 2019 06:33:36 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B5B4880511 for ; Thu, 7 Feb 2019 11:33:18 +0000 (UTC) Date: Thu, 7 Feb 2019 11:33:12 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Message-ID: <20190207113312.GD19438@redhat.com> Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20190206132331.1694-1-quintela@redhat.com> <20190206132331.1694-2-quintela@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190206132331.1694-2-quintela@redhat.com> Subject: Re: [Qemu-devel] [PATCH 1/4] multifd: Change page count default to 128 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Juan Quintela Cc: qemu-devel@nongnu.org, Laurent Vivier , Thomas Huth , Markus Armbruster , "Dr. David Alan Gilbert" , Paolo Bonzini On Wed, Feb 06, 2019 at 02:23:28PM +0100, Juan Quintela wrote: > I haven't seend any problem about using 64 or 128. And it make much > less contention on the locks. Just change it. Isn't there a issue with having a fixed page count given the very different default page sizes across architectures ? x86 is 4kb pages, while ppc64 uses 64kb pages IIUC. This would mean current value of 64 pages, would correspond to 1/4 MB on x86, and 4 MB on ppc64. The new value would be 1/2 MB on x86 and 8 MB on ppc64. Should we instead be measuring this tunable in units that are independant of page size ? eg meansure in KB, with a requirement that the value is a multiple of the page size. Then set the default to 512 KB ? > > Signed-off-by: Juan Quintela > --- > migration/migration.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/migration/migration.c b/migration/migration.c > index ef1d53cde2..f673486679 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -81,7 +81,7 @@ > /* The delay time (in ms) between two COLO checkpoints */ > #define DEFAULT_MIGRATE_X_CHECKPOINT_DELAY (200 * 100) > #define DEFAULT_MIGRATE_MULTIFD_CHANNELS 2 > -#define DEFAULT_MIGRATE_MULTIFD_PAGE_COUNT 16 > +#define DEFAULT_MIGRATE_MULTIFD_PAGE_COUNT 128 > > /* Background transfer rate for postcopy, 0 means unlimited, note > * that page requests can still exceed this limit. > -- > 2.20.1 > > Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|