From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758187Ab1ILPnq (ORCPT ); Mon, 12 Sep 2011 11:43:46 -0400 Received: from static-76-160-165-106.dsl.cavtel.net ([76.160.165.106]:51444 "EHLO static-76-160-165-106.dsl.cavtel.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757971Ab1ILPnp (ORCPT ); Mon, 12 Sep 2011 11:43:45 -0400 Message-ID: <4E6E28AE.4040608@metrics.net> Date: Mon, 12 Sep 2011 11:43:42 -0400 From: Anthony DeRobertis User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.21) Gecko/20110831 Icedove/3.1.13 MIME-Version: 1.0 To: Linux-kernel mailing list Subject: Re: RFC: [PATCH] Add a sysfs entry queue/ignore_flushes. References: <4E6A783D.9040708@metrics.net> <20110911050829.GA15269@kroah.com> In-Reply-To: <20110911050829.GA15269@kroah.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/11/2011 01:08 AM, Greg KH wrote: > If you add/remove/change sysfs attributes, you also need to do the same > to Documentation/ABI. I've added in documentation. Not sure who to set Contact: to, if that should be the maintainer of the block layer or me, or... Here is the updated patch, with documentation: commit bd69b2eea10cfa217e91f82bac62b32800cb26bb Author: Anthony DeRobertis Date: Fri Sep 9 10:54:25 2011 -0400 Add a sysfs entry queue/ignore_flushes. Set to ignore_flushes to 1 to have the block layer silently discard REQ_FLUSH and REQ_FUA. Great speed increase at the risk of great data loss. Defaults to 0, of course. Signed-off-by: Anthony DeRobertis diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block index c1eb41c..b0da935 100644 --- a/Documentation/ABI/testing/sysfs-block +++ b/Documentation/ABI/testing/sysfs-block @@ -206,3 +206,14 @@ Description: when a discarded area is read the discard_zeroes_data parameter will be set to one. Otherwise it will be 0 and the result of reading a discarded area is undefined. + +What: /sys/block//queue/ignore_flushes +Date: September 2011 +Contact: +Description: + When this is set to 0 (the default), the device will + honor flush and force unit access (FUA) requests. When + set to 1, flush and FUA requests will be silently + ignored. Ignoring these requests potentially bosts + performance at the cost of data integrity if the machine + crashes or loses power. diff --git a/block/blk-core.c b/block/blk-core.c index 90e1ffd..fd4f1c1 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1515,9 +1515,11 @@ static inline void __generic_make_request(struct bio *bio) /* * Filter flush bio's early so that make_request based * drivers without flush support don't have to worry - * about them. + * about them. Also filter if configured to ignore flushes. */ - if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) { + if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && + (!q->flush_flags || + test_bit(QUEUE_FLAG_IGNORE_FLUSH, &q->queue_flags))) { bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA); if (!nr_sectors) { err = 0; diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 0ee17b5..8f19827 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -214,6 +214,7 @@ queue_store_##name(struct request_queue *q, const char *page, size_t count) \ QUEUE_SYSFS_BIT_FNS(nonrot, NONROT, 1); QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0); +QUEUE_SYSFS_BIT_FNS(ignore_flushes, IGNORE_FLUSH, 0); QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0); #undef QUEUE_SYSFS_BIT_FNS @@ -385,6 +386,12 @@ static struct queue_sysfs_entry queue_random_entry = { .store = queue_store_random, }; +static struct queue_sysfs_entry queue_ignore_flushes_entry = { + .attr = {.name = "ignore_flushes", .mode = S_IRUGO | S_IWUSR }, + .show = queue_show_ignore_flushes, + .store = queue_store_ignore_flushes, +}; + static struct attribute *default_attrs[] = { &queue_requests_entry.attr, &queue_ra_entry.attr, @@ -407,6 +414,7 @@ static struct attribute *default_attrs[] = { &queue_rq_affinity_entry.attr, &queue_iostats_entry.attr, &queue_random_entry.attr, + &queue_ignore_flushes_entry.attr, NULL, }; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 84b15d5..61b39e0 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -408,6 +408,7 @@ struct request_queue { #define QUEUE_FLAG_ADD_RANDOM 16 /* Contributes to random pool */ #define QUEUE_FLAG_SECDISCARD 17 /* supports SECDISCARD */ #define QUEUE_FLAG_SAME_FORCE 18 /* force complete on same CPU */ +#define QUEUE_FLAG_IGNORE_FLUSH 19 /* ignore REQ_FLUSH and REQ_FUA */ #define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ (1 << QUEUE_FLAG_STACKABLE) | \