Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752066Ab3GHNFQ (ORCPT ); Mon, 8 Jul 2013 09:05:16 -0400 Received: from smtp.eu.citrix.com ([46.33.159.39]:56110 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751872Ab3GHNFN (ORCPT ); Mon, 8 Jul 2013 09:05:13 -0400 X-IronPort-AV: E=Sophos;i="4.87,1020,1363132800"; d="scan'208";a="6453383" From: Roger Pau Monne To: , CC: Roger Pau Monne , Konrad Rzeszutek Wilk Subject: [PATCH RFC 3/4] xen-blkfront: prevent hoarding all grants Date: Mon, 8 Jul 2013 15:03:26 +0200 Message-ID: <1373288607-1876-4-git-send-email-roger.pau@citrix.com> X-Mailer: git-send-email 1.7.7.5 (Apple Git-26) In-Reply-To: <1373288607-1876-1-git-send-email-roger.pau@citrix.com> References: <1373288607-1876-1-git-send-email-roger.pau@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1886 Lines: 52 Prevent blkfront from hoarding all grants by adding a minimum number of grants that must be free at all times. We still need a way to free unused grants in blkfront, but this patch will mitigate the problem in the meantime. Signed-off-by: Roger Pau Monné Cc: Konrad Rzeszutek Wilk --- drivers/block/xen-blkfront.c | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 187a437..3d445c0 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -101,6 +101,12 @@ MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE) /* + * Make sure there are at least MIN_FREE_GRANTS at all times, preventing + * blkfront from hoarding all grants + */ +#define MIN_FREE_GRANTS 512 + +/* * We have one of these per vbd, whether ide, scsi or 'other'. They * hang in private_data off the gendisk structure. We may end up * putting all kinds of interesting stuff here :-) @@ -412,13 +418,13 @@ static int blkif_queue_request(struct request *req) if (info->persistent_gnts_c < max_grefs) { new_persistent_gnts = 1; if (gnttab_alloc_grant_references( - max_grefs - info->persistent_gnts_c, + max_grefs - info->persistent_gnts_c + MIN_FREE_GRANTS, &gref_head) < 0) { gnttab_request_free_callback( &info->callback, blkif_restart_queue_callback, info, - max_grefs); + max_grefs + MIN_FREE_GRANTS); return 1; } } else -- 1.7.7.5 (Apple Git-26) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/