From patchwork Mon Mar 27 17:51:37 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shaohua Li X-Patchwork-Id: 9647299 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id A9B42602BF for ; Mon, 27 Mar 2017 17:54:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9B0A2283C9 for ; Mon, 27 Mar 2017 17:54:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9002228408; Mon, 27 Mar 2017 17:54:29 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BDD30283C9 for ; Mon, 27 Mar 2017 17:54:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751945AbdC0RyF (ORCPT ); Mon, 27 Mar 2017 13:54:05 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:57671 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751553AbdC0RxV (ORCPT ); Mon, 27 Mar 2017 13:53:21 -0400 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v2RHjBlN015183 for ; Mon, 27 Mar 2017 10:51:49 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=S5neT/hFnNOksA0x2FeIFI+oA3y/H0djOcjU0Ql/VCs=; b=p9TWsi+dtR/LQBqYvmAiwkpt28CWmHjJJ1jRTx2q+NND1puI67Rr256OKXPoLM0RKuTg r5nS2uCu1K+hZeF7MRKp2sgMt45HG5p0ohK7nytdWfOOeHOsvs6pqL3/bQW4s5wFBdFC iJVsylbI87FW599KWZKb0JTToH+L3/5fYTE= Received: from mail.thefacebook.com ([199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 29f4eu0wrm-8 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Mon, 27 Mar 2017 10:51:48 -0700 Received: from mx-out.facebook.com (192.168.52.123) by PRN-CHUB10.TheFacebook.com (192.168.16.20) with Microsoft SMTP Server (TLS) id 14.3.319.2; Mon, 27 Mar 2017 10:51:47 -0700 Received: from facebook.com (2401:db00:21:603d:face:0:19:0) by mx-out.facebook.com (10.102.107.99) with ESMTP id 0bf36aac131611e7a29c0002c99293a0-bc9fd9a0 for ; Mon, 27 Mar 2017 10:51:46 -0700 Received: by devbig638.prn2.facebook.com (Postfix, from userid 11222) id C2E0A43A3BAE; Mon, 27 Mar 2017 10:51:46 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Shaohua Li Smtp-Origin-Hostname: devbig638.prn2.facebook.com To: , CC: , , Vivek Goyal , , Smtp-Origin-Cluster: prn2c22 Subject: [PATCH V7 09/18] blk-throttle: make throtl_slice tunable Date: Mon, 27 Mar 2017 10:51:37 -0700 Message-ID: <0c1c990f15fff70b4c0a5a50984f3803420db3f3.1490634565.git.shli@fb.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: References: X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-03-27_16:, , signatures=0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP throtl_slice is important for blk-throttling. It's called slice internally but it really is a time window blk-throttling samples data. blk-throttling will make decision based on the samplings. An example is bandwidth measurement. A cgroup's bandwidth is measured in the time interval of throtl_slice. A small throtl_slice meanse cgroups have smoother throughput but burn more CPUs. It has 100ms default value, which is not appropriate for all disks. A fast SSD can dispatch a lot of IOs in 100ms. This patch makes it tunable. Since throtl_slice isn't a time slice, the sysfs name 'throttle_sample_time' reflects its character better. Signed-off-by: Shaohua Li --- Documentation/block/queue-sysfs.txt | 6 +++ block/blk-sysfs.c | 11 ++++++ block/blk-throttle.c | 79 ++++++++++++++++++++++++++----------- block/blk.h | 5 +++ 4 files changed, 79 insertions(+), 22 deletions(-) diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt index c0a3bb5..b7f6bdc 100644 --- a/Documentation/block/queue-sysfs.txt +++ b/Documentation/block/queue-sysfs.txt @@ -192,5 +192,11 @@ scaling back writes. Writing a value of '0' to this file disables the feature. Writing a value of '-1' to this file resets the value to the default setting. +throttle_sample_time (RW) +------------------------- +This is the time window that blk-throttle samples data, in millisecond. +blk-throttle makes decision based on the samplings. Lower time means cgroups +have more smooth throughput, but higher CPU overhead. This exists only when +CONFIG_BLK_DEV_THROTTLING_LOW is enabled. Jens Axboe , February 2009 diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index fa831cb..b315e62 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -677,6 +677,14 @@ static struct queue_sysfs_entry queue_wb_lat_entry = { .store = queue_wb_lat_store, }; +#ifdef CONFIG_BLK_DEV_THROTTLING_LOW +static struct queue_sysfs_entry throtl_sample_time_entry = { + .attr = {.name = "throttle_sample_time", .mode = S_IRUGO | S_IWUSR }, + .show = blk_throtl_sample_time_show, + .store = blk_throtl_sample_time_store, +}; +#endif + static struct attribute *default_attrs[] = { &queue_requests_entry.attr, &queue_ra_entry.attr, @@ -710,6 +718,9 @@ static struct attribute *default_attrs[] = { &queue_dax_entry.attr, &queue_wb_lat_entry.attr, &queue_poll_delay_entry.attr, +#ifdef CONFIG_BLK_DEV_THROTTLING_LOW + &throtl_sample_time_entry.attr, +#endif NULL, }; diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 2073b48..93841da 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -19,7 +19,8 @@ static int throtl_grp_quantum = 8; static int throtl_quantum = 32; /* Throttling is performed over 100ms slice and after that slice is renewed */ -static unsigned long throtl_slice = HZ/10; /* 100 ms */ +#define DFL_THROTL_SLICE (HZ / 10) +#define MAX_THROTL_SLICE (HZ) static struct blkcg_policy blkcg_policy_throtl; @@ -162,6 +163,8 @@ struct throtl_data /* Total Number of queued bios on READ and WRITE lists */ unsigned int nr_queued[2]; + unsigned int throtl_slice; + /* Work for dispatching throttled bios */ struct work_struct dispatch_work; unsigned int limit_index; @@ -590,7 +593,7 @@ static void throtl_dequeue_tg(struct throtl_grp *tg) static void throtl_schedule_pending_timer(struct throtl_service_queue *sq, unsigned long expires) { - unsigned long max_expire = jiffies + 8 * throtl_slice; + unsigned long max_expire = jiffies + 8 * sq_to_tg(sq)->td->throtl_slice; /* * Since we are adjusting the throttle limit dynamically, the sleep @@ -658,7 +661,7 @@ static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg, if (time_after_eq(start, tg->slice_start[rw])) tg->slice_start[rw] = start; - tg->slice_end[rw] = jiffies + throtl_slice; + tg->slice_end[rw] = jiffies + tg->td->throtl_slice; throtl_log(&tg->service_queue, "[%c] new slice with credit start=%lu end=%lu jiffies=%lu", rw == READ ? 'R' : 'W', tg->slice_start[rw], @@ -670,7 +673,7 @@ static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw) tg->bytes_disp[rw] = 0; tg->io_disp[rw] = 0; tg->slice_start[rw] = jiffies; - tg->slice_end[rw] = jiffies + throtl_slice; + tg->slice_end[rw] = jiffies + tg->td->throtl_slice; throtl_log(&tg->service_queue, "[%c] new slice start=%lu end=%lu jiffies=%lu", rw == READ ? 'R' : 'W', tg->slice_start[rw], @@ -680,13 +683,13 @@ static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw) static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw, unsigned long jiffy_end) { - tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); + tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice); } static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw, unsigned long jiffy_end) { - tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); + tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice); throtl_log(&tg->service_queue, "[%c] extend slice start=%lu end=%lu jiffies=%lu", rw == READ ? 'R' : 'W', tg->slice_start[rw], @@ -726,19 +729,20 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) * is bad because it does not allow new slice to start. */ - throtl_set_slice_end(tg, rw, jiffies + throtl_slice); + throtl_set_slice_end(tg, rw, jiffies + tg->td->throtl_slice); time_elapsed = jiffies - tg->slice_start[rw]; - nr_slices = time_elapsed / throtl_slice; + nr_slices = time_elapsed / tg->td->throtl_slice; if (!nr_slices) return; - tmp = tg_bps_limit(tg, rw) * throtl_slice * nr_slices; + tmp = tg_bps_limit(tg, rw) * tg->td->throtl_slice * nr_slices; do_div(tmp, HZ); bytes_trim = tmp; - io_trim = (tg_iops_limit(tg, rw) * throtl_slice * nr_slices) / HZ; + io_trim = (tg_iops_limit(tg, rw) * tg->td->throtl_slice * nr_slices) / + HZ; if (!bytes_trim && !io_trim) return; @@ -753,7 +757,7 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) else tg->io_disp[rw] = 0; - tg->slice_start[rw] += nr_slices * throtl_slice; + tg->slice_start[rw] += nr_slices * tg->td->throtl_slice; throtl_log(&tg->service_queue, "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu", @@ -773,9 +777,9 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, /* Slice has just started. Consider one slice interval */ if (!jiffy_elapsed) - jiffy_elapsed_rnd = throtl_slice; + jiffy_elapsed_rnd = tg->td->throtl_slice; - jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); + jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice); /* * jiffy_elapsed_rnd should not be a big value as minimum iops can be @@ -822,9 +826,9 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, /* Slice has just started. Consider one slice interval */ if (!jiffy_elapsed) - jiffy_elapsed_rnd = throtl_slice; + jiffy_elapsed_rnd = tg->td->throtl_slice; - jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); + jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice); tmp = tg_bps_limit(tg, rw) * jiffy_elapsed_rnd; do_div(tmp, HZ); @@ -890,8 +894,10 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, if (throtl_slice_used(tg, rw) && !(tg->service_queue.nr_queued[rw])) throtl_start_new_slice(tg, rw); else { - if (time_before(tg->slice_end[rw], jiffies + throtl_slice)) - throtl_extend_slice(tg, rw, jiffies + throtl_slice); + if (time_before(tg->slice_end[rw], + jiffies + tg->td->throtl_slice)) + throtl_extend_slice(tg, rw, + jiffies + tg->td->throtl_slice); } if (tg_with_in_bps_limit(tg, bio, &bps_wait) && @@ -1632,7 +1638,7 @@ static bool throtl_can_upgrade(struct throtl_data *td, if (td->limit_index != LIMIT_LOW) return false; - if (time_before(jiffies, td->low_downgrade_time + throtl_slice)) + if (time_before(jiffies, td->low_downgrade_time + td->throtl_slice)) return false; rcu_read_lock(); @@ -1689,8 +1695,9 @@ static bool throtl_tg_can_downgrade(struct throtl_grp *tg) * If cgroup is below low limit, consider downgrade and throttle other * cgroups */ - if (time_after_eq(now, td->low_upgrade_time + throtl_slice) && - time_after_eq(now, tg_last_low_overflow_time(tg) + throtl_slice)) + if (time_after_eq(now, td->low_upgrade_time + td->throtl_slice) && + time_after_eq(now, tg_last_low_overflow_time(tg) + + td->throtl_slice)) return true; return false; } @@ -1719,13 +1726,14 @@ static void throtl_downgrade_check(struct throtl_grp *tg) return; if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) return; - if (time_after(tg->last_check_time + throtl_slice, now)) + if (time_after(tg->last_check_time + tg->td->throtl_slice, now)) return; elapsed_time = now - tg->last_check_time; tg->last_check_time = now; - if (time_before(now, tg_last_low_overflow_time(tg) + throtl_slice)) + if (time_before(now, tg_last_low_overflow_time(tg) + + tg->td->throtl_slice)) return; if (tg->bps[READ][LIMIT_LOW]) { @@ -1953,6 +1961,7 @@ int blk_throtl_init(struct request_queue *q) q->td = td; td->queue = q; + td->throtl_slice = DFL_THROTL_SLICE; td->limit_valid[LIMIT_MAX] = true; td->limit_index = LIMIT_MAX; @@ -1973,6 +1982,32 @@ void blk_throtl_exit(struct request_queue *q) kfree(q->td); } +#ifdef CONFIG_BLK_DEV_THROTTLING_LOW +ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page) +{ + if (!q->td) + return -EINVAL; + return sprintf(page, "%u\n", jiffies_to_msecs(q->td->throtl_slice)); +} + +ssize_t blk_throtl_sample_time_store(struct request_queue *q, + const char *page, size_t count) +{ + unsigned long v; + unsigned long t; + + if (!q->td) + return -EINVAL; + if (kstrtoul(page, 10, &v)) + return -EINVAL; + t = msecs_to_jiffies(v); + if (t == 0 || t > MAX_THROTL_SLICE) + return -EINVAL; + q->td->throtl_slice = t; + return count; +} +#endif + static int __init throtl_init(void) { kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); diff --git a/block/blk.h b/block/blk.h index d1ea4bd9..bcd3de6 100644 --- a/block/blk.h +++ b/block/blk.h @@ -324,5 +324,10 @@ static inline void blk_throtl_drain(struct request_queue *q) { } static inline int blk_throtl_init(struct request_queue *q) { return 0; } static inline void blk_throtl_exit(struct request_queue *q) { } #endif /* CONFIG_BLK_DEV_THROTTLING */ +#ifdef CONFIG_BLK_DEV_THROTTLING_LOW +extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page); +extern ssize_t blk_throtl_sample_time_store(struct request_queue *q, + const char *page, size_t count); +#endif #endif /* BLK_INTERNAL_H */