From nobody Fri Nov 7 09:09:00 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 154747510285615.42988545026617; Mon, 14 Jan 2019 06:11:42 -0800 (PST) Received: from localhost ([127.0.0.1]:35245 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gj2xp-0007g5-NM for importer@patchew.org; Mon, 14 Jan 2019 09:11:41 -0500 Received: from eggs.gnu.org ([209.51.188.92]:47436) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gj2ls-0007H1-0u for qemu-devel@nongnu.org; Mon, 14 Jan 2019 08:59:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gj2lr-0004wp-1j for qemu-devel@nongnu.org; Mon, 14 Jan 2019 08:59:19 -0500 Received: from smtp03.citrix.com ([162.221.156.55]:1411) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gj2lq-0004wI-QQ for qemu-devel@nongnu.org; Mon, 14 Jan 2019 08:59:18 -0500 X-IronPort-AV: E=Sophos;i="5.56,477,1539648000"; d="scan'208";a="75507052" From: Anthony PERARD To: Date: Mon, 14 Jan 2019 13:51:54 +0000 Message-ID: <20190114135154.16826-26-anthony.perard@citrix.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190114135154.16826-1-anthony.perard@citrix.com> References: <20190114135154.16826-1-anthony.perard@citrix.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 162.221.156.55 Subject: [Qemu-devel] [PULL 25/25] xen-block: avoid repeated memory allocation X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Anthony PERARD , xen-devel@lists.xenproject.org, Peter Maydell Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" From: Tim Smith The xen-block dataplane currently allocates memory to hold the data for each request as that request is used, and frees it afterwards. Because it requires page-aligned blocks, this interacts poorly with non-page- aligned allocations and balloons the heap. Instead, allocate the maximum possible buffer size required for the protocol, which is BLKIF_MAX_SEGMENTS_PER_REQUEST (currently 11) pages when the request structure is created, and keep that buffer until it is destroyed. Since the requests are re-used via a free list, this should actually improve memory usage. Signed-off-by: Tim Smith Re-based and commit comment adjusted. Signed-off-by: Paul Durrant Acked-by: Anthony PERARD Signed-off-by: Anthony PERARD --- hw/block/dataplane/xen-block.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/hw/block/dataplane/xen-block.c b/hw/block/dataplane/xen-block.c index 35bfccfba7..d0d8905a33 100644 --- a/hw/block/dataplane/xen-block.c +++ b/hw/block/dataplane/xen-block.c @@ -70,7 +70,6 @@ static void reset_request(XenBlockRequest *request) memset(&request->req, 0, sizeof(request->req)); request->status =3D 0; request->start =3D 0; - request->buf =3D NULL; request->size =3D 0; request->presync =3D 0; =20 @@ -95,6 +94,14 @@ static XenBlockRequest *xen_block_start_request(XenBlock= DataPlane *dataplane) /* allocate new struct */ request =3D g_malloc0(sizeof(*request)); request->dataplane =3D dataplane; + /* + * We cannot need more pages per requests than this, and since we + * re-use requests, allocate the memory once here. It will be freed + * xen_block_dataplane_destroy() when the request list is freed. + */ + request->buf =3D qemu_memalign(XC_PAGE_SIZE, + BLKIF_MAX_SEGMENTS_PER_REQUEST * + XC_PAGE_SIZE); dataplane->requests_total++; qemu_iovec_init(&request->v, 1); } else { @@ -272,14 +279,12 @@ static void xen_block_complete_aio(void *opaque, int = ret) if (ret =3D=3D 0) { xen_block_copy_request(request); } - qemu_vfree(request->buf); break; case BLKIF_OP_WRITE: case BLKIF_OP_FLUSH_DISKCACHE: if (!request->req.nr_segments) { break; } - qemu_vfree(request->buf); break; default: break; @@ -360,12 +365,10 @@ static int xen_block_do_aio(XenBlockRequest *request) { XenBlockDataPlane *dataplane =3D request->dataplane; =20 - request->buf =3D qemu_memalign(XC_PAGE_SIZE, request->size); if (request->req.nr_segments && (request->req.operation =3D=3D BLKIF_OP_WRITE || request->req.operation =3D=3D BLKIF_OP_FLUSH_DISKCACHE) && xen_block_copy_request(request)) { - qemu_vfree(request->buf); goto err; } =20 @@ -665,6 +668,7 @@ void xen_block_dataplane_destroy(XenBlockDataPlane *dat= aplane) request =3D QLIST_FIRST(&dataplane->freelist); QLIST_REMOVE(request, list); qemu_iovec_destroy(&request->v); + qemu_vfree(request->buf); g_free(request); } =20 --=20 Anthony PERARD