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| author | Jan Kara <jack@suse.cz> | 2024-07-01 13:50:48 +0300 |
|---|---|---|
| committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2024-07-08 20:47:27 +0300 |
| commit | 2f1f31042ef07719a0d5cb4784b8a32d20c13110 (patch) | |
| tree | 7a7fe9889f6136d8a61c991b0f9c1ee4afa0841c /include | |
| parent | f8a3955083f5cc5d62257c6e1103f89f566d3a87 (diff) | |
| download | linux-2f1f31042ef07719a0d5cb4784b8a32d20c13110.tar.xz | |
nfs: Block on write congestion
Commit 6df25e58532b ("nfs: remove reliance on bdi congestion")
introduced NFS-private solution for limiting number of writes
outstanding against a particular server. Unlike previous bdi congestion
this algorithm actually works and limits number of outstanding writeback
pages to nfs_congestion_kb which scales with amount of client's memory
and is capped at 256 MB. As a result some workloads such as random
buffered writes over NFS got slower (from ~170 MB/s to ~126 MB/s). The
fio command to reproduce is:
fio --direct=0 --ioengine=sync --thread --invalidate=1 --group_reporting=1
--runtime=300 --fallocate=posix --ramp_time=10 --new_group --rw=randwrite
--size=64256m --numjobs=4 --bs=4k --fsync_on_close=1 --end_fsync=1
This happens because the client sends ~256 MB worth of dirty pages to
the server and any further background writeback request is ignored until
the number of writeback pages gets below the threshold of 192 MB. By the
time this happens and clients decides to trigger another round of
writeback, the server often has no pages to write and the disk is idle.
To fix this problem and make the client react faster to eased congestion
of the server by blocking waiting for congestion to resolve instead of
aborting writeback. This improves the random 4k buffered write
throughput to 184 MB/s.
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/nfs_fs_sb.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h index ba9df1848b35..1df86ab98c77 100644 --- a/include/linux/nfs_fs_sb.h +++ b/include/linux/nfs_fs_sb.h @@ -140,6 +140,7 @@ struct nfs_server { struct rpc_clnt * client_acl; /* ACL RPC client handle */ struct nlm_host *nlm_host; /* NLM client handle */ struct nfs_iostats __percpu *io_stats; /* I/O statistics */ + wait_queue_head_t write_congestion_wait; /* wait until write congestion eases */ atomic_long_t writeback; /* number of writeback pages */ unsigned int write_congested;/* flag set when writeback gets too high */ unsigned int flags; /* various flags */ |