[Bugs] [Bug 1393419] read-ahead not working if open-behind is turned on

bugzilla at redhat.com bugzilla at redhat.com
Tue Jul 25 11:26:21 UTC 2017


https://bugzilla.redhat.com/show_bug.cgi?id=1393419

Milind Changire <mchangir at redhat.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mchangir at redhat.com



--- Comment #5 from Milind Changire <mchangir at redhat.com> ---
here's output of a single run as per test case in comment #0
(without dropping kernel caches):
(all nodes are virtual machines on a single laptop with SSD)

16:17:46 [root at f25node1 ~] # gluster volume info dist-rep

Volume Name: dist-rep
Type: Distributed-Replicate
Volume ID: 54b4340d-cb1f-4742-a0ca-3d3ac499d84c
Status: Started
Snapshot Count: 0
Number of Bricks: 2 x 3 = 6
Transport-type: tcp
Bricks:
Brick1: f25node1:/glustervols/dist-rep/brick
Brick2: f25node2:/glustervols/dist-rep/brick
Brick3: f25node3:/glustervols/dist-rep/brick
Brick4: f25node4:/glustervols/dist-rep/brick
Brick5: f25node5:/glustervols/dist-rep/brick
Brick6: f25node6:/glustervols/dist-rep/brick
Options Reconfigured:
performance.open-behind: off
performance.read-ahead-page-count: 16
transport.address-family: inet
nfs.disable: on
cluster.brick-multiplex: off

15:11:17 [root at f25client1 ~] # mount -t glusterfs f25node1:/dist-rep
/mnt/dist-rep

performance.read-ahead-page-count       4                                      

15:13:46 [root at f25client1 ~] # dd if=/dev/zero of=/mnt/dist-rep/1g bs=1M
count=1K
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 263.88 s, 4.1 MB/s

performance.read-ahead-page-count       1

16:07:16 [root at f25client1 ~] # dd if=/mnt/dist-rep/1g bs=1M of=/dev/null
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 10.1683 s, 106 MB/s

performance.read-ahead-page-count       16

16:14:31 [root at f25client1 ~] # dd if=/mnt/dist-rep/1g bs=1M of=/dev/null
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 0.162729 s, 6.6 GB/s

performance.open-behind                 off
performance.read-ahead-page-count       16

16:18:38 [root at f25client1 ~] # dd if=/mnt/dist-rep/1g bs=1M of=/dev/null
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 6.43123 s, 167 MB/s

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