Messages in this thread |  | | Date | Wed, 22 Oct 2014 22:02:19 +0200 | From | Peter Zijlstra <> | Subject | Re: perf: Translating mmap2 ids into socket info? |
| |
On Wed, Oct 22, 2014 at 02:09:35PM -0400, Joe Mario wrote: > >Yes, kernel memory is directly addresses, you basically have a static > >address->node mapping, it never changes. > > For kernel addresses, is there a reason not to have it available in perf, > especially when that knowledge is important to understanding a numa-related slowdown?
Dunno why that isn't exposed in sysfs.
> In our case, when we booted with one configuration, AIM ran fine. When we > booted another way, AIM's performance dropped 50%. It was all due to the dentry > lock being located on a different (now remote) numa node. > > We used your dmesg approach to track down the home node in an attempt to understand > what was different between the two boots. But the problem would have been obvious > if perf simply listed the home node info.
Or if you'd used more counters that track the node interconnect traffic ;-) There are a few simple ones that count local/remote type things (offcore), but using the uncore counters you can track way more.
|  |