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spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:47336 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hoWtB-0002qQ-RW for qemu-devel@archiver.kernel.org; Fri, 19 Jul 2019 13:41:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57271) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hoWt2-0002Qt-7S for qemu-devel@nongnu.org; Fri, 19 Jul 2019 13:41:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hoWt0-0001qs-2B for qemu-devel@nongnu.org; Fri, 19 Jul 2019 13:41:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56212) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hoWsx-0001kK-Lq for qemu-devel@nongnu.org; Fri, 19 Jul 2019 13:41:37 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BD2053082B4B; Fri, 19 Jul 2019 17:41:31 +0000 (UTC) Received: from work-vm (ovpn-117-245.ams2.redhat.com [10.36.117.245]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CF33C5C219; Fri, 19 Jul 2019 17:41:30 +0000 (UTC) Date: Fri, 19 Jul 2019 18:41:28 +0100 From: "Dr. David Alan Gilbert" To: Wei Yang Message-ID: <20190719174128.GI3000@work-vm> References: <20190710081111.10302-1-richardw.yang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <20190710081111.10302-1-richardw.yang@linux.intel.com> User-Agent: Mutt/1.12.0 (2019-05-25) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Fri, 19 Jul 2019 17:41:31 +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: > Even we need to do discard for each RAMBlock, we still can leverage the > same memory space to store the information. >=20 > By doing so, we avoid memory allocation and deallocation to the system > and also avoid potential failure of memory allocation which breaks the > migration. >=20 > Signed-off-by: Wei Yang > --- > migration/postcopy-ram.c | 16 +++++++--------- > 1 file changed, 7 insertions(+), 9 deletions(-) >=20 > 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(MigrationIncoming= State *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 bit= map. > * @name: RAMBlock that discards will operate on. > * > * returns: a new PDS. > @@ -1386,13 +1385,14 @@ void postcopy_fault_thread_notify(MigrationIncomi= ngState *mis) > PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms, > const char *name) > { > - PostcopyDiscardState *res =3D g_malloc0(sizeof(PostcopyDiscardState)= ); > + static PostcopyDiscardState res =3D {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 =66rom postcopy_discard_send_range and friends? If there's only one pds then we don't need to pass the pointer around. Dave > - if (res) { > - res->ramblock_name =3D name; > - } > + res.ramblock_name =3D name; > + res.cur_entry =3D 0; > + res.nsentwords =3D 0; > + res.nsentcmds =3D 0; > =20 > - return res; > + return &res; > } > =20 > /** > @@ -1449,8 +1449,6 @@ void postcopy_discard_send_finish(MigrationState *m= s, PostcopyDiscardState *pds) > =20 > trace_postcopy_discard_send_finish(pds->ramblock_name, pds->nsentwor= ds, > pds->nsentcmds); > - > - g_free(pds); > } > =20 > /* > --=20 > 2.17.1 >=20 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK