Re: BUG: Slowdown on 3000 socket-machines tracked down

Christian Schmid
2005-03-11T19:31:46Z

Ben Greear wrote:
> Christian Schmid wrote:
>
>> OHGAWD I GOT IT!!!!!!!!
>>
>> I admit, totally coincidentially but its really FIXED. Today I went to
>> the puter scanning the servers by routine and wondered why the
>> bandwidth is at 100% without any holes.
>>
>> The only thing I have done is I switched off hyper-threading because
>> the server is at only 20% CPU anyway so I just disabled it.
>>
>> So its something with linux dealing with hyper-threading. YAY :)
>
>
> For what it's worth, I was running dual-xeon systems with HT turned on.
>
> But, I have a single process, single-threaded application, so there is
> not much
> scheduling to be done. If you have a large number of threads or processes,
> then it would make more sense for turning off HT to have an affect.

This effect appeared on 1 task and on 200 tasks. I dont know what it is, but with HT off it doesnt
appear anymore. The slow-down still appears when lower_zone_protection is set to 0 but the peak at
80 MB disappeared when set to 1024. I am now running at 95 MB/Sec smoothly.

Chris