On Wed, 2008-09-17 at 14:49 +0200, Ingo Molnar wrote: > * 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: Yeah, as sure as I can be. I've built both (et al) kernels several times, and it has repeated every time. Would be nice if someone would try to confirm/deny though. For my little quad, I do.. #!/bin/sh echo 0 > /proc/sys/kernel/sched_wakeup_granularity_ns netserver -p 12865 netserver -p 12866 netserver -p 12867 netserver -p 12868 netperf -p 12865 -t TCP_RR -l 60 -H 127.0.0.1 -T 0,0 -- -r 1,1& netperf -p 12866 -t TCP_RR -l 60 -H 127.0.0.1 -T 1,1 -- -r 1,1& netperf -p 12867 -t TCP_RR -l 60 -H 127.0.0.1 -T 2,2 -- -r 1,1& netperf -p 12868 -t TCP_RR -l 60 -H 127.0.0.1 -T 3,3 -- -r 1,1& wait killall netserver > 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. I sure hope it's something like ping-pong, it's driving me NUTS. -Mike -- 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
