On 11/3/18 4:43 AM, Matt Macy wrote:
Author: mmacy
Date: Sat Nov 3 03:43:32 2018
New Revision: 340097
URL: https://svnweb.freebsd.org/changeset/base/340097
Log:
Convert epoch to read / write records per cpu
In discussing D17503 "Run epoch calls sooner and more reliably" with
sbahra@ we came to the conclusion that epoch is currently misusing the
ck_epoch API. It isn't safe to do a "write side" operation (ck_epoch_call
or ck_epoch_poll) in the middle of a "read side" section. Since, by
definition,
it's possible to be preempted during the middle of an EPOCH_PREEMPT
epoch the GC task might call ck_epoch_poll or another thread might call
ck_epoch_call on the same section. The right solution is ultimately to change
the way that ck_epoch works for this use case. However, as a stopgap for
12 we agreed to simply have separate records for each use case.
Tested by: pho@
MFC after: 3 days
^^^ not yet MFC'ed - any reason why not?
--HPS
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