Comparing with kernel 2.6.24, tbench result has regression with
2.6.25-rc1.
1) On 2 quad-core processor stoakley: 4%.
2) On 4 quad-core processor tigerton: more than 30%.
bisect located below patch.
b4ce92775c2e7ff9cf79cca4e0a19c8c5fd6287b is first bad commit
commit b4ce92775c2e7ff9cf79cca4e0a19c8c5fd6287b
Author: Herbert Xu <[EMAIL PROTECTED]>
Date: Tue Nov 13 21:33:32 2007 -0800
[IPV6]: Move nfheader_len into rt6_info
The dst member nfheader_len is only used by IPv6. It's also currently
creating a rather ugly alignment hole in struct dst. Therefore this patch
moves it from there into struct rt6_info.
As tbench uses ipv4, so the patch's real impact on ipv4 is it deletes
nfheader_len in dst_entry. It might change cache line alignment.
To verify my finding, I just added nfheader_len back to dst_entry in 2.6.25-rc1
and reran tbench on the 2 machines. Performance could be recovered completely.
I started cpu_number*2 tbench processes. On my 16-core tigerton:
#./tbench_srv &
#./tbench 32 127.0.0.1
-yanmin
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