On 3/20/2015 8:15 PM, Konstantin Belousov wrote:
For the purpose of devfs, does it make sense to bump timestamps like
normal filesystems for each read/write operation? Looks like Mac OS X
will bump timestamps for each operation but Debian don't.
First question is, what timecounter hardware is used. I would accept
some slowdown from hardware like HPET, but it is indeed surprising
if caused by TSC.
David Wolfskill suggested trying the problem commit with
vfs.timestamp_precision=0
and it does indeed restore performance to what it was. The raw dtrace
files are available and FlameGraphs can all be found at
http://tancsa.com/time/
---Mike
--
-------------------
Mike Tancsa, tel +1 519 651 3400
Sentex Communications, m...@sentex.net
Providing Internet services since 1994 www.sentex.net
Cambridge, Ontario Canada http://www.tancsa.com/
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