Author: jhb
Date: Tue Apr 5 00:08:42 2016
New Revision: 297568
URL: https://svnweb.freebsd.org/changeset/base/297568
Log:
Don't wakeup the fdc worker thread once a second when idle.
The fdc worker thread was using a one second timeout while waiting for
a new bio to arrive or for the device to detach. However, the driver
already does a wakeup when queueing a new bio or asking the thread to
detach, so the timeout only served to waste CPU time waking up the
thread once a second just so it could go right back to sleep. Use an
infinite timeout instead.
Discussed with: phk
Sponsored by: Netflix
Modified:
head/sys/dev/fdc/fdc.c
Modified: head/sys/dev/fdc/fdc.c
==============================================================================
--- head/sys/dev/fdc/fdc.c Mon Apr 4 23:55:32 2016 (r297567)
+++ head/sys/dev/fdc/fdc.c Tue Apr 5 00:08:42 2016 (r297568)
@@ -968,7 +968,7 @@ fdc_worker(struct fdc_data *fdc)
fdc->bp = bioq_takefirst(&fdc->head);
if (fdc->bp == NULL)
msleep(&fdc->head, &fdc->fdc_mtx,
- PRIBIO, "-", hz);
+ PRIBIO, "-", 0);
} while (fdc->bp == NULL &&
(fdc->flags & FDC_KTHREAD_EXIT) == 0);
mtx_unlock(&fdc->fdc_mtx);
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