[OpenAFS-devel] delays and lost contact with fileserver with 1.3.84 and higher

[Alexander Bergolth]

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On 10/31/2005 02:17 PM, Jeffrey Altman wrote:
> Alexander Bergolth wrote:
>>On 10/31/2005 10:11 AM, Harald Barth wrote:
>>>>Chas wrote to me, but I think that's more useful for you.
>>>>
>>>>>>I'd like to hear more about the changes to rx that were made between
>>>>>>82 and 84, what was the intended outcome?
>>>>>
>>>>>there does seem to be one set of changes that is outside the scope of the
>>>>>rx packet queue changes.  it a long shot, but you could revert it and see
>>>>>if that  helps.
>>>>>
>>>>>http://www.openafs.org/cgi-bin/cvsweb.cgi/openafs/src/rx/rx.c.diff?r1=1.22.2.30&r2=1.22.2.31
>>>>>
>>>>>	DELTA STABLE12-rx-makecall-race-fix-20050518 AUTHOR
> 
> This patch is most certainly not related to your problems.  The patch
> removes a race condition that allowed rx threads to sleep forever.

It is this patch that causes the stalls on my system:

http://www.openafs.org/cgi-bin/cvsweb.cgi/openafs/src/rx/rx.c#rev1.58.2.19

- -------------------- snipp! --------------------
DELTA STABLE14-rx-fpq-bulk-free-20050529
AUTHOR tkeiser@psu.edu
FIXES 19027

After profiling RX for a while, I've found a few more bottlenecks in the
packet handling code.  This patch addresses a couple of these issues.
The major change in this patch is a new API to allow bulk packet
alloc/free ops on rx_queue's of packets.  Benefits include reduced lock
contention on rx_freePktQ_lock, elimination of a lot of unnecessary cache
line invalidates, and reduced register window thrashing on sparc.

In addition, this patch dedicates one rx_packet per thread to rxi_SendAck,
since that function is in the critical path, and represents a large
percentage of execution time.
- -------------------- snipp! --------------------

http://www.openafs.org/cgi-bin/cvsweb.cgi/openafs/src/rx/rx.c.diff?r1=1.58.2.18&r2=1.58.2.19


I reverted it in 1.3.84 and now the delays are gone.

Cheers,
- --leo
- --
- -----------------------------------------------------------------------
Alexander.Bergolth@wu-wien.ac.at                Fax: +43-1-31336-906050
Zentrum fuer Informatikdienste - Wirtschaftsuniversitaet Wien - Austria

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