Disable timestamping on devfs by default.
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Authored by delphij on Mar 21 2015, 12:26 AM.

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Reviewers

kib
jhb

Summary

Currently we update timestamps unconditionally for each
read/write on devfs. This may slow things down on hardware where
reading time is expensive (e.g. HPET, because the timestamp setting
is currently nanosecond by default) with limited benefit.

Test Plan

boot system and change the setting from zero to non-zero
and back and observe the performance impact.

Diff Detail

Repository

rS FreeBSD src repository - subversion

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delphij updated this revision to Diff 4314.Mar 21 2015, 12:26 AM

delphij retitled this revision from to Disable timestamping on devfs by default..

delphij updated this object.

delphij edited the test plan for this revision. (Show Details)

delphij added a reviewer: jhb.

Herald added a subscriber: imp. · View Herald TranscriptMar 21 2015, 12:26 AM

delphij added a reviewer: kib.Mar 21 2015, 12:33 AM

kib added inline comments.Mar 21 2015, 12:43 AM

sys/fs/devfs/devfs_vnops.c
1592	I suggest not to skip timestamp on attribute change always.

Exclude the VOP_SETATTR() codepath.

delphij added inline comments.Mar 21 2015, 12:47 AM

sys/fs/devfs/devfs_vnops.c
1592	Actually the current code doesn't seem right. I'll exclude this portion for now.

kib accepted this revision.Mar 21 2015, 12:50 AM

kib edited edge metadata.

This revision is now accepted and ready to land.Mar 21 2015, 12:50 AM

Closed by commit rS280308.

Revision Contents
Changeset List

Path

Size

sys/

fs/

devfs/

devfs_devs.c

2 lines

devfs_vnops.c

13 lines

Diff 4315

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sys/fs/devfs/devfs_devs.c