From patchwork Wed Dec 12 11:16:26 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 1011841 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=citrix.com Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 43FDpy57JCz9s3Z for ; Wed, 12 Dec 2018 22:19:22 +1100 (AEDT) Received: from localhost ([::1]:43891 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gX2Xw-0000Aw-BH for incoming@patchwork.ozlabs.org; Wed, 12 Dec 2018 06:19:20 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34977) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gX2VK-0006q9-4k for qemu-devel@nongnu.org; Wed, 12 Dec 2018 06:16:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gX2VJ-0003HK-2X for qemu-devel@nongnu.org; Wed, 12 Dec 2018 06:16:38 -0500 Received: from smtp03.citrix.com ([162.221.156.55]:43645) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gX2VG-0002eF-NQ; Wed, 12 Dec 2018 06:16:34 -0500 X-IronPort-AV: E=Sophos;i="5.56,344,1539648000"; d="scan'208";a="73098903" From: Paul Durrant To: , , Date: Wed, 12 Dec 2018 11:16:26 +0000 Message-ID: <1544613386-22045-4-git-send-email-paul.durrant@citrix.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1544613386-22045-1-git-send-email-paul.durrant@citrix.com> References: <1544613386-22045-1-git-send-email-paul.durrant@citrix.com> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 162.221.156.55 Subject: [Qemu-devel] [PATCH v3 3/3] 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: Kevin Wolf , Stefano Stabellini , Tim Smith , Max Reitz , Paul Durrant , Stefan Hajnoczi , Anthony Perard Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" 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 --- Cc: Stefan Hajnoczi Cc: Stefano Stabellini Cc: Anthony Perard Cc: Kevin Wolf Cc: Max Reitz --- 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 b4ff2e3..21804d7 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 = 0; request->start = 0; - request->buf = NULL; request->size = 0; request->presync = 0; @@ -95,6 +94,14 @@ static XenBlockRequest *xen_block_start_request(XenBlockDataPlane *dataplane) /* allocate new struct */ request = g_malloc0(sizeof(*request)); request->dataplane = 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 = 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 == 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 = request->dataplane; - request->buf = qemu_memalign(XC_PAGE_SIZE, request->size); if (request->req.nr_segments && (request->req.operation == BLKIF_OP_WRITE || request->req.operation == BLKIF_OP_FLUSH_DISKCACHE) && xen_block_copy_request(request)) { - qemu_vfree(request->buf); goto err; } @@ -665,6 +668,7 @@ void xen_block_dataplane_destroy(XenBlockDataPlane *dataplane) request = QLIST_FIRST(&dataplane->freelist); QLIST_REMOVE(request, list); qemu_iovec_destroy(&request->v); + qemu_vfree(request->buf); g_free(request); }