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spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:45126 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hpwvs-0006W5-6D for qemu-devel@archiver.kernel.org; Tue, 23 Jul 2019 11:42:28 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49988) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hpwvh-00067f-WD for qemu-devel@nongnu.org; Tue, 23 Jul 2019 11:42:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hpwvg-0001We-Ri for qemu-devel@nongnu.org; Tue, 23 Jul 2019 11:42:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59056) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hpwvg-0001WI-Jc for qemu-devel@nongnu.org; Tue, 23 Jul 2019 11:42:16 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E4BC0308FBAF; Tue, 23 Jul 2019 15:42:15 +0000 (UTC) Received: from work-vm (ovpn-117-202.ams2.redhat.com [10.36.117.202]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E61F319C58; Tue, 23 Jul 2019 15:42:14 +0000 (UTC) Date: Tue, 23 Jul 2019 16:42:12 +0100 From: "Dr. David Alan Gilbert" To: Wei Yang Message-ID: <20190723154212.GL2719@work-vm> References: <20190710081111.10302-1-richardw.yang@linux.intel.com> <20190719174128.GI3000@work-vm> <20190722063941.GA2602@richard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190722063941.GA2602@richard> User-Agent: Mutt/1.12.0 (2019-05-25) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Tue, 23 Jul 2019 15:42:15 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH] migration/postcopy: use static PostcopyDiscardState instead of allocating it for each block X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Wei Yang (richardw.yang@linux.intel.com) wrote: > On Fri, Jul 19, 2019 at 06:41:28PM +0100, Dr. David Alan Gilbert wrote: > >* Wei Yang (richardw.yang@linux.intel.com) wrote: > >> Even we need to do discard for each RAMBlock, we still can leverage the > >> same memory space to store the information. > >> > >> By doing so, we avoid memory allocation and deallocation to the system > >> and also avoid potential failure of memory allocation which breaks the > >> migration. > >> > >> Signed-off-by: Wei Yang > >> --- > >> migration/postcopy-ram.c | 16 +++++++--------- > >> 1 file changed, 7 insertions(+), 9 deletions(-) > >> > >> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c > >> index 9faacacc9e..2e6b076bb7 100644 > >> --- a/migration/postcopy-ram.c > >> +++ b/migration/postcopy-ram.c > >> @@ -1377,8 +1377,7 @@ void postcopy_fault_thread_notify(MigrationIncomingState *mis) > >> * asking to discard individual ranges. > >> * > >> * @ms: The current migration state. > >> - * @offset: the bitmap offset of the named RAMBlock in the migration > >> - * bitmap. > >> + * @offset: the bitmap offset of the named RAMBlock in the migration bitmap. > >> * @name: RAMBlock that discards will operate on. > >> * > >> * returns: a new PDS. > >> @@ -1386,13 +1385,14 @@ void postcopy_fault_thread_notify(MigrationIncomingState *mis) > >> PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms, > >> const char *name) > >> { > >> - PostcopyDiscardState *res = g_malloc0(sizeof(PostcopyDiscardState)); > >> + static PostcopyDiscardState res = {0}; > > > >Do you think it would be better to make this a static at the top of > >migration/postcopy-ram.c and then we could remove the pds parameters > >from postcopy_discard_send_range and friends? > > Just took a look into this one. One problem is not all its friends are in > migration/postcopy-ram.c > > For example, postcopy_chunk_hostpages_pass() is in migration/ram.c. But doesn't that just pass teh pds back to postcopy_discard_send_range which is in postcopy-ram ? Dave > Which way do you prefer? > > >If there's only one pds then we don't need to pass the pointer around. > > > >Dave > > > >> - if (res) { > >> - res->ramblock_name = name; > >> - } > >> + res.ramblock_name = name; > >> + res.cur_entry = 0; > >> + res.nsentwords = 0; > >> + res.nsentcmds = 0; > >> > >> - return res; > >> + return &res; > >> } > >> > >> /** > >> @@ -1449,8 +1449,6 @@ void postcopy_discard_send_finish(MigrationState *ms, PostcopyDiscardState *pds) > >> > >> trace_postcopy_discard_send_finish(pds->ramblock_name, pds->nsentwords, > >> pds->nsentcmds); > >> - > >> - g_free(pds); > >> } > >> > >> /* > >> -- > >> 2.17.1 > >> > >-- > >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > -- > Wei Yang > Help you, Help me -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK