O(1) scheduler gives big boost to tbench 192
Quoted 2 lines · Robert Love
Quoted 1 line
It is just for pipes we previously used sync, no?
On Tue, 7 May 2002 16:48:57 -0700, Mike Kravetz wrote
Quoted 7 lines
That's the only thing I know of that used it.
I'd really like to know if there are any real workloads that benefited from this feature, rather than just some benchmark. I can do some research, but was hoping someone on this list might remember. If there is a valid workload, I'll propose a patch.
Quoted 2 lines · J.A. Magallon
- Re-introduction of
wake_up_syncto make pipes run fast again. No idea about this is useful or not, that is the point, to test it
2.4.19-pre8-jam2 showed slightly better performance on the quad Xeon for most benchmarks with 25-wake_up_sync backed out. However, it's not clear to me 25-wake_up_sync was proper patch to backout for this test, as there wasn't a dramatic change in Pipe latency or bandwidth without it.
There was a > 300% improvement lmbench Pipe bandwidth and latency comparing pre8-jam2 to pre7-jam6.
Average of 25 lmbench runs on jam2 kernels, 12 on the others:
2.4.19-pre8-jam2-nowuos (backed out 25-wake_up_sync patch)
*Local* Communication latencies in microseconds - smaller is better
AF
kernel Pipe UNIX ----------------------- ----- ----- 2.4.19-pre7-jam6 29.51 42.37 2.4.19-pre8 10.73 29.94 2.4.19-pre8-aa2 12.45 29.53 2.4.19-pre8-ac1 35.39 45.59 2.4.19-pre8-jam2 7.70 15.27 2.4.19-pre8-jam2-nowuos 7.74 14.93
*Local* Communication bandwidths in MB/s - bigger is better
AF
kernel Pipe UNIX
----------------------- ------ ------ 2.4.19-pre7-jam6 66.41 260.39 2.4.19-pre8 468.57 273.32 2.4.19-pre8-aa2 418.09 273.59 2.4.19-pre8-ac1 110.62 241.06 2.4.19-pre8-jam2 545.66 233.68 2.4.19-pre8-jam2-nowuos 544.57 246.53
The kernel build test, which applies patches through a pipe and compiles with -pipe didn't reflect an improvement.
kernel average min_time max_time runs notes 2.4.19-pre7-jam6 237.0 235 239 3 All successful 2.4.19-pre8 239.7 238 241 3 All successful 2.4.19-pre8-aa2 237.7 237 238 3 All successful 2.4.19-pre8-ac1 239.3 238 241 3 All successful 2.4.19-pre8-jam2 240.0 238 241 3 All successful 2.4.19-pre8-jam2-nowuos 238.7 236 241 3 All successful
I don't know how much of the kernel build test is dependant on pipe performance. There is probably a better "real world" measurement.
On a single processor box, there was an improvement on kernel build between pre7-jam6 and pre8-jam2. That was only on one sample though.
Xeon page:
http://home.earthlink.net/~rwhron/kernel/bigbox.html
Latest on uniproc:
http://home.earthlink.net/~rwhron/kernel/latest.html
Signature · 1 line
Randy Hron