Deadlocks with recent SMP current
julian at elischer.org
Tue Aug 17 10:10:52 PDT 2004
Sławek Żak wrote:
> Martin Blapp <mb at imp.ch> writes:
>>Since yesterday I'm getting complete deadlocks. This time unrelated
>>the servers are nor loaded at all, the just freeze after a while.
>>No break into DDB possible at all.
> Despite the numerous reports of current problems I'm running 5.2-CURRENT for
> 12 days now without a glitch. Tested overnight with 2 buildworlds running
> with -j8. It's a 2 processor Xeon server with 4BSD scheduler. Just my .02
> Another thing is bothering me. In top I see:
> CPU states: 16.2% user, 0.0% nice, 2.5% system, 1.0% interrupt, 80.3% idle
> Mem: 254M Active, 605M Inact, 254M Wired, 16K Cache, 112M Buf, 2622M Free
> Swap: 4096M Total, 4096M Free
> PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU CPU COMMAND
> 37033 mysql 20 0 265M 178M kserel 0 610:59 124.37% 124.37% mysqld
> MySQLd is running with libpthread and can go up to 400% without
> significantly afecting the idle percentage shown by top. I don't see how I
> could fit 400% into 20% on those two suckers, therefore I ask :)
Cpu percentage use is broken for pthread applications..
it's almost impossible to work out the right way of doing it
due to the nature of M:N threading where there is no fixed rule as
to which user thread is run by which kernel thread.
I have ideas but it will probably have to be an aggreagate cpu% for the thread
group, divided by the number of kernel threads in the group.
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