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

From: Christian Schmid
Date: Fri Mar 11 2005 - 14:35:01 EST

Ben Greear wrote:
Christian Schmid wrote:


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.

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