On Mon, 18 Apr 2011, Alexander Motin wrote:
On 18.04.2011 20:06, John Baldwin wrote:
On Monday, April 18, 2011 9:34:31 am Alexander Motin wrote:
Author: mav
Date: Mon Apr 18 13:34:31 2011
New Revision: 220777
URL: http://svn.freebsd.org/changeset/base/220777
Log:
- Tune different wait loops to cut some more milliseconds from reset
time.
- Do not call ahci_start() before device signature received. It is
required
by the specification and caused non-fatal reset timeouts on AMD
chipsets.
Do you have to use DELAY() here rather than a blocking sleep via pause()?
At the moment I would say yes. These paths are called from CAM while holding
SIM lock. CAM may not like if I drop the lock in the middle of the call. Also
during recovery those functions could be called from the callout and
interrupt threads. In that case even dropping the lock won't allow thread to
sleep.
More than before you reduced the delays. There seems to be no interrupt
for reset, and it may be impossible for a timer to interrupt after
only ~10 usec like some of the reduced delays use.
I will think more about possibilities to refactor the code to replace some
DELAYs with callouts, but requirement to keep functionality in polled mode
doesn't make the task easier.
This means that callouts cannot work. Dumps should start with a reset
which should run entirely in polled mode, like the entired dump.
Bruce
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