From: Wu Fengguang <fengguang.wu@intel.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>, Jens Axboe <axboe@kernel.dk>,
Chris Mason <chris.mason@oracle.com>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
Christoph Hellwig <hch@lst.de>,
Dave Chinner <david@fromorbit.com>, Theodore Ts'o <tytso@mit.edu>,
Mel Gorman <mel@csn.ul.ie>, Rik van Riel <riel@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Greg Thelen <gthelen@google.com>,
Minchan Kim <minchan.kim@gmail.com>,
Vivek Goyal <vgoyal@redhat.com>,
Andrea Righi <arighi@develer.com>,
Balbir Singh <balbir@linux.vnet.ibm.com>,
linux-mm <linux-mm@kvack.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 09/27] nfs: writeback pages wait queue
Date: Fri, 4 Mar 2011 10:01:58 +0800 [thread overview]
Message-ID: <20110304020157.GB7976@localhost> (raw)
In-Reply-To: <1299168481.1310.56.camel@laptop>
On Fri, Mar 04, 2011 at 12:08:01AM +0800, Peter Zijlstra wrote:
> On Thu, 2011-03-03 at 14:45 +0800, Wu Fengguang wrote:
> > +static void nfs_wakeup_congested(long nr,
> > + struct backing_dev_info *bdi,
> > + wait_queue_head_t *wqh)
> > +{
> > + long limit = nfs_congestion_kb >> (PAGE_SHIFT - 10);
> > +
> > + if (nr < 2 * limit - min(limit / 8, NFS_WAIT_PAGES)) {
> > + if (test_bit(BDI_sync_congested, &bdi->state)) {
> > + clear_bdi_congested(bdi, BLK_RW_SYNC);
> > + smp_mb__after_clear_bit();
> > + }
> > + if (waitqueue_active(&wqh[BLK_RW_SYNC]))
> > + wake_up(&wqh[BLK_RW_SYNC]);
> > + }
> > + if (nr < limit - min(limit / 8, NFS_WAIT_PAGES)) {
> > + if (test_bit(BDI_async_congested, &bdi->state)) {
> > + clear_bdi_congested(bdi, BLK_RW_ASYNC);
> > + smp_mb__after_clear_bit();
> > + }
> > + if (waitqueue_active(&wqh[BLK_RW_ASYNC]))
> > + wake_up(&wqh[BLK_RW_ASYNC]);
> > + }
> > +}
>
> memory barriers want a comment - always - explaining what they order and
> against whoem.
OK. Added this comment:
clear_bdi_congested(bdi, BLK_RW_SYNC);
/*
* On the following wake_up(), nfs_wait_congested()
* will see the cleared bit and quit.
*/
smp_mb__after_clear_bit();
}
if (waitqueue_active(&wqh[BLK_RW_SYNC]))
wake_up(&wqh[BLK_RW_SYNC]);
Thanks,
Fengguang
---
Subject: nfs: writeback pages wait queue
Date: Tue Aug 03 22:47:07 CST 2010
The generic writeback routines are departing from congestion_wait()
in preference of get_request_wait(), aka. waiting on the block queues.
Introduce the missing writeback wait queue for NFS, otherwise its
writeback pages will grow out of control, exhausting all PG_dirty pages.
CC: Jens Axboe <axboe@kernel.dk>
CC: Chris Mason <chris.mason@oracle.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
fs/nfs/client.c | 2
fs/nfs/write.c | 97 +++++++++++++++++++++++++++++++-----
include/linux/nfs_fs_sb.h | 1
3 files changed, 89 insertions(+), 11 deletions(-)
--- linux-next.orig/fs/nfs/write.c 2011-03-03 14:44:16.000000000 +0800
+++ linux-next/fs/nfs/write.c 2011-03-04 09:58:38.000000000 +0800
@@ -185,11 +185,72 @@ static int wb_priority(struct writeback_
* NFS congestion control
*/
+#define NFS_WAIT_PAGES (1024L >> (PAGE_SHIFT - 10))
int nfs_congestion_kb;
-#define NFS_CONGESTION_ON_THRESH (nfs_congestion_kb >> (PAGE_SHIFT-10))
-#define NFS_CONGESTION_OFF_THRESH \
- (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
+/*
+ * SYNC requests will block on (2*limit) and wakeup on (2*limit-NFS_WAIT_PAGES)
+ * ASYNC requests will block on (limit) and wakeup on (limit - NFS_WAIT_PAGES)
+ * In this way SYNC writes will never be blocked by ASYNC ones.
+ */
+
+static void nfs_set_congested(long nr, struct backing_dev_info *bdi)
+{
+ long limit = nfs_congestion_kb >> (PAGE_SHIFT - 10);
+
+ if (nr > limit && !test_bit(BDI_async_congested, &bdi->state))
+ set_bdi_congested(bdi, BLK_RW_ASYNC);
+ else if (nr > 2 * limit && !test_bit(BDI_sync_congested, &bdi->state))
+ set_bdi_congested(bdi, BLK_RW_SYNC);
+}
+
+static void nfs_wait_congested(int is_sync,
+ struct backing_dev_info *bdi,
+ wait_queue_head_t *wqh)
+{
+ int waitbit = is_sync ? BDI_sync_congested : BDI_async_congested;
+ DEFINE_WAIT(wait);
+
+ if (!test_bit(waitbit, &bdi->state))
+ return;
+
+ for (;;) {
+ prepare_to_wait(&wqh[is_sync], &wait, TASK_UNINTERRUPTIBLE);
+ if (!test_bit(waitbit, &bdi->state))
+ break;
+
+ io_schedule();
+ }
+ finish_wait(&wqh[is_sync], &wait);
+}
+
+static void nfs_wakeup_congested(long nr,
+ struct backing_dev_info *bdi,
+ wait_queue_head_t *wqh)
+{
+ long limit = nfs_congestion_kb >> (PAGE_SHIFT - 10);
+
+ if (nr < 2 * limit - min(limit / 8, NFS_WAIT_PAGES)) {
+ if (test_bit(BDI_sync_congested, &bdi->state)) {
+ clear_bdi_congested(bdi, BLK_RW_SYNC);
+ /*
+ * On the following wake_up(), nfs_wait_congested()
+ * will see the cleared bit and quit.
+ */
+ smp_mb__after_clear_bit();
+ }
+ if (waitqueue_active(&wqh[BLK_RW_SYNC]))
+ wake_up(&wqh[BLK_RW_SYNC]);
+ }
+ if (nr < limit - min(limit / 8, NFS_WAIT_PAGES)) {
+ if (test_bit(BDI_async_congested, &bdi->state)) {
+ clear_bdi_congested(bdi, BLK_RW_ASYNC);
+ smp_mb__after_clear_bit();
+ }
+ if (waitqueue_active(&wqh[BLK_RW_ASYNC]))
+ wake_up(&wqh[BLK_RW_ASYNC]);
+ }
+}
static int nfs_set_page_writeback(struct page *page)
{
@@ -200,11 +261,8 @@ static int nfs_set_page_writeback(struct
struct nfs_server *nfss = NFS_SERVER(inode);
page_cache_get(page);
- if (atomic_long_inc_return(&nfss->writeback) >
- NFS_CONGESTION_ON_THRESH) {
- set_bdi_congested(&nfss->backing_dev_info,
- BLK_RW_ASYNC);
- }
+ nfs_set_congested(atomic_long_inc_return(&nfss->writeback),
+ &nfss->backing_dev_info);
}
return ret;
}
@@ -216,8 +274,10 @@ static void nfs_end_page_writeback(struc
end_page_writeback(page);
page_cache_release(page);
- if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
- clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
+
+ nfs_wakeup_congested(atomic_long_dec_return(&nfss->writeback),
+ &nfss->backing_dev_info,
+ nfss->writeback_wait);
}
static struct nfs_page *nfs_find_and_lock_request(struct page *page, bool nonblock)
@@ -318,19 +378,34 @@ static int nfs_writepage_locked(struct p
int nfs_writepage(struct page *page, struct writeback_control *wbc)
{
+ struct inode *inode = page->mapping->host;
+ struct nfs_server *nfss = NFS_SERVER(inode);
int ret;
ret = nfs_writepage_locked(page, wbc);
unlock_page(page);
+
+ nfs_wait_congested(wbc->sync_mode == WB_SYNC_ALL,
+ &nfss->backing_dev_info,
+ nfss->writeback_wait);
+
return ret;
}
-static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
+static int nfs_writepages_callback(struct page *page,
+ struct writeback_control *wbc, void *data)
{
+ struct inode *inode = page->mapping->host;
+ struct nfs_server *nfss = NFS_SERVER(inode);
int ret;
ret = nfs_do_writepage(page, wbc, data);
unlock_page(page);
+
+ nfs_wait_congested(wbc->sync_mode == WB_SYNC_ALL,
+ &nfss->backing_dev_info,
+ nfss->writeback_wait);
+
return ret;
}
--- linux-next.orig/include/linux/nfs_fs_sb.h 2011-03-03 14:44:15.000000000 +0800
+++ linux-next/include/linux/nfs_fs_sb.h 2011-03-03 14:44:16.000000000 +0800
@@ -102,6 +102,7 @@ struct nfs_server {
struct nfs_iostats __percpu *io_stats; /* I/O statistics */
struct backing_dev_info backing_dev_info;
atomic_long_t writeback; /* number of writeback pages */
+ wait_queue_head_t writeback_wait[2];
int flags; /* various flags */
unsigned int caps; /* server capabilities */
unsigned int rsize; /* read size */
--- linux-next.orig/fs/nfs/client.c 2011-03-03 14:44:15.000000000 +0800
+++ linux-next/fs/nfs/client.c 2011-03-03 14:44:16.000000000 +0800
@@ -1042,6 +1042,8 @@ static struct nfs_server *nfs_alloc_serv
INIT_LIST_HEAD(&server->delegations);
atomic_set(&server->active, 0);
+ init_waitqueue_head(&server->writeback_wait[BLK_RW_SYNC]);
+ init_waitqueue_head(&server->writeback_wait[BLK_RW_ASYNC]);
server->io_stats = nfs_alloc_iostats();
if (!server->io_stats) {
next prev parent reply other threads:[~2011-03-04 2:01 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-03 6:45 [PATCH 00/27] IO-less dirty throttling v6 Wu Fengguang
2011-03-03 6:45 ` [PATCH 01/27] writeback: add bdi_dirty_limit() kernel-doc Wu Fengguang
2011-03-03 6:45 ` [PATCH 02/27] writeback: avoid duplicate balance_dirty_pages_ratelimited() calls Wu Fengguang
2011-03-03 6:45 ` [PATCH 03/27] writeback: skip balance_dirty_pages() for in-memory fs Wu Fengguang
2011-03-03 6:45 ` [PATCH 04/27] writeback: reduce per-bdi dirty threshold ramp up time Wu Fengguang
2011-03-03 6:45 ` [PATCH 05/27] btrfs: avoid duplicate balance_dirty_pages_ratelimited() calls Wu Fengguang
2011-03-03 6:45 ` [PATCH 06/27] btrfs: lower the dirty balance poll interval Wu Fengguang
2011-03-04 6:22 ` Dave Chinner
2011-03-04 7:57 ` Wu Fengguang
2011-03-03 6:45 ` [PATCH 07/27] btrfs: wait on too many nr_async_bios Wu Fengguang
2011-03-03 6:45 ` [PATCH 08/27] nfs: dirty livelock prevention is now done in VFS Wu Fengguang
2011-03-03 6:45 ` [PATCH 09/27] nfs: writeback pages wait queue Wu Fengguang
2011-03-03 16:07 ` Peter Zijlstra
2011-03-04 1:53 ` Wu Fengguang
2011-03-03 16:08 ` Peter Zijlstra
2011-03-04 2:01 ` Wu Fengguang [this message]
2011-03-04 9:10 ` Peter Zijlstra
2011-03-04 9:26 ` Peter Zijlstra
2011-03-04 14:38 ` Wu Fengguang
2011-03-04 14:41 ` Peter Zijlstra
2011-03-03 6:45 ` [PATCH 10/27] nfs: limit the commit size to reduce fluctuations Wu Fengguang
2011-03-03 6:45 ` [PATCH 11/27] nfs: limit the commit range Wu Fengguang
2011-03-03 6:45 ` [PATCH 12/27] nfs: lower writeback threshold proportionally to dirty threshold Wu Fengguang
2011-03-03 6:45 ` [PATCH 13/27] writeback: account per-bdi accumulated written pages Wu Fengguang
2011-03-03 6:45 ` [PATCH 14/27] writeback: account per-bdi accumulated dirtied pages Wu Fengguang
2011-03-03 6:45 ` [PATCH 15/27] writeback: bdi write bandwidth estimation Wu Fengguang
2011-03-03 6:45 ` [PATCH 16/27] writeback: smoothed global/bdi dirty pages Wu Fengguang
2011-03-03 6:45 ` [PATCH 17/27] writeback: smoothed dirty threshold and limit Wu Fengguang
2011-03-03 6:45 ` [PATCH 18/27] writeback: enforce 1/4 gap between the dirty/background thresholds Wu Fengguang
2011-03-03 6:45 ` [PATCH 19/27] writeback: dirty throttle bandwidth control Wu Fengguang
2011-03-07 21:34 ` Wu Fengguang
2011-03-29 21:08 ` Wu Fengguang
2011-03-03 6:45 ` [PATCH 20/27] writeback: IO-less balance_dirty_pages() Wu Fengguang
2011-03-03 6:45 ` [PATCH 21/27] writeback: show bdi write bandwidth in debugfs Wu Fengguang
2011-03-03 6:45 ` [PATCH 22/27] writeback: trace dirty_throttle_bandwidth Wu Fengguang
2011-03-03 6:45 ` [PATCH 23/27] writeback: trace balance_dirty_pages Wu Fengguang
2011-03-03 6:45 ` [PATCH 24/27] writeback: trace global_dirty_state Wu Fengguang
2011-03-03 6:45 ` [PATCH 25/27] writeback: make nr_to_write a per-file limit Wu Fengguang
2011-03-03 6:45 ` [PATCH 26/27] writeback: scale IO chunk size up to device bandwidth Wu Fengguang
2011-03-03 6:45 ` [PATCH 27/27] writeback: trace writeback_single_inode Wu Fengguang
2011-03-03 20:12 ` [PATCH 00/27] IO-less dirty throttling v6 Vivek Goyal
2011-03-03 20:48 ` Vivek Goyal
2011-03-04 9:06 ` Wu Fengguang
2011-04-04 18:12 ` async write IO controllers Wu Fengguang
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