Commit Graph

56 Commits

Author SHA1 Message Date
Brian Behlendorf d05ec4b45f Assume TQ_SLEEP when not explicitly specified. 2010-04-23 14:39:47 -07:00
Brian Behlendorf 82387586af Optimize lowest outstanding taskqid calculation in taskq_lowest_id()
In the initial version of taskq_lowest_id() the entire pending and
work list was locked under the tq->tq_lock to determine the lowest
outstanding taskqid.  At the time this done because I was rushed
and wanted to make sure it was right... fast was secondary.  Well now
fast is important too so I carefully thought through the pending
and work list management and convinced myself it is safe and correct
to simply check the first entry.  I added a large comment to the source
to explain this.  But basically as long as we are careful to ensure the
pending and work list stay sorted this is safe and fast.

The motivation for this chance was that I was observing as much as
10% of the total CPU time go to waiting on the tq->tq_lock when the
pending list was long.  This resolves that problems and frees up
that CPU time for something useful.
2010-01-04 15:52:26 -08:00
Brian Behlendorf 915404bd50 Add basic support for TASKQ_THREADS_CPU_PCT taskq flag which is
used to scale the number of threads based on the number of online
CPUs.  As CPUs are added/removed we should rescale the thread
count appropriately, but currently this is only done at create.
2009-07-09 10:07:52 -07:00
Brian Behlendorf 7257ec4185 Fix taskq_wait() not waiting bug
I'm very surprised this has not surfaced until now.  But the taskq_wait()
implementation work only wait successfully the first time it was called.
Subsequent usage of taskq_wait() on the taskq would not wait.

The issue was caused by tq->tq_lowest_id being set to MAX_INT after the
first wait completed.  This caused subsequent waits which check that the
waiting id is less than the lowest taskq id to always succeed.  The fix
is to ensure that tq->tq_lowest_id is never set larger than tq->tq_next.id.

Additional fixes which were added to this patch include:
1) Fix a race by placing the taskq_wait_check() in the tq->tq_lock spinlock.
2) taskq_wait() should wait for the largest outstanding id.
3) Multiple spelling corrections.
4) Added taskq wait regression test to validate correct behavior.
2009-03-15 15:13:49 -07:00
Brian Behlendorf f220894e1f Make the number of system taskq threads based on the node of cores in the node, as is done for most linux system tasks 2009-02-02 08:53:53 -08:00
Brian Behlendorf 617d5a673c Rename modules to module and update references 2009-01-15 10:44:54 -08:00