Messages in this thread | | | Date | Tue, 6 Aug 2002 14:47:14 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: IPC lock patch performance improvement |
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On Mon, 5 Aug 2002, Duc Vianney wrote: > I ran the LMbench Pipe and IPC latency test bucket against the IPC lock > patch from Mingming Cao and found the patch improves the performance of > those functions from 1% to 9%. See the attached data. The kernel under > test is 2.5.29, SMP kernel running on a 4-way 500 MHz. The data for > 2.5.29s4-ipc represents the average of three runs. > > Percent > 2.5.29s4 2.5.29s4-ipc Improvement > Pipe latency 12.51 11.43 9% > AF_Unix sock stream latency 21.61 19.82 8% > UDP latency using localhost 36.28 35.12 3% > TCP latency using localhost 56.90 54.89 4% > RPC/tcp latency using local host 123.30 121.91 1% > RPC/udp latency using localhost 89.78 88.70 1% > TCP/IP connection cost to localhost 192.74 187.76 3% > Note: Latency is in microseconds > Note: 2.5.29s4 is the base 2.5.29 SMP kernel running on a 4-way, > 2.5.29s4-ipc is the base 2.5.29 SMP kernel built with IPC lock patch.
Please show me I'm wrong, but so far as I can see (from source and breakpoints) LMbench never touches the SysV IPC code, which is the only code affected by Mingming's proposed IPC locking changes. I believe LMbench tests InterProcessCommunication via pipes and sockets, not via the SysV IPC msg sem and shm.
If that's right, then your improvement is magical; but we can hope for even better when the appropriate codepaths are tested.
Hugh
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