* Mike Galbraith <efault@xxxxxx> wrote: > > It looks like a potentially bogus bisection result, but _maybe_ it > > has relevance: changes the size of "struct security_operations", > > which could have alignment and layout effects on all sorts of kernel > > variables, kmalloc sizes, etc. > > This may well be a mythical creature infestation for all I know ;-), > but it's address is somewhere in the 2069f45..847106f block, 316 > commits, none of which look like they should be the least bit > interesting to netperf. I reverted this particular commit in 27.git, > got the expected result. Looks like I'll keep poking at it, can't > seem to resist. Grr. are you sure it's 2069f45..847106f? Filtering out the likely-uninteresting commits: git log --pretty=format:"%h: %s" 2069f45..847106f | grep -viE \ 'block|alsa|pcmcia|sound|Merge|iosched|blk|DAC960|scsi|s390|paride|pktcdvd|filter|cdrom|drm' gives us: 7daf705: Start using the new '%pS' infrastructure to print symbols 6f0f0fd: security: remove register_security hook 93cbace: security: remove dummy module fix 5915eb5: security: remove dummy module b478a9f: security: remove unused sb_get_mnt_opts hook 32502b8: splice: fix generic_file_splice_read() race with page invalidation 8b3d356: ramfs: enable splice write a144ff0: xen: Avoid allocations causing swap activity on the resume path which really only leaves that security commit your bisection fingered. Which _slightly_ raises its likelyhood of being implicated. Structure size changes can move two formerly far-apart netperf-relevant symbols on the same cacheline, which can start cache ping-pong-ing badly. It wouldnt be the first such incident - alignment changes impacting macro benchmarks. (and it's hard to find it as the thing that changes alignment/size/sharedness might be something totally unrelated) It's still a bit too early to say this for sure though ... Ingo -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
