Messages in this thread | | | Date | Fri, 3 Jul 2015 18:21:48 +0800 | From | Hou Pengyang <> | Subject | Re: [RFC] perf tools: Add hugetlbfs memory recognition |
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On 2015/6/30 22:50, Arnaldo Carvalho de Melo wrote: > Em Tue, Jun 30, 2015 at 05:33:05PM +0800, Hou Pengyang escreveu: >> On 2015/6/29 21:42, Arnaldo Carvalho de Melo wrote: >>> Em Mon, Jun 29, 2015 at 10:23:29AM -0300, Arnaldo Carvalho de Melo escreveu: >>>> Em Sat, Jun 27, 2015 at 05:08:20PM +0800, Hou Pengyang escreveu: >>>>> So I wonder if there is a need to read /proc/pid/smaps instead of >>>>> /proc/pid/maps to generate MMAP2 event. Or we should solve the problem by >>>>> another way? >>>> >>>> Doing some research now... >>> >>> Bummer, seems that only smaps -> ... -> show_smap_vma_flags() will >>> expose that to userspace... >>> >>> Perhaps we can look at some global stat for HugeTLB fs to figure out if >>> we really, really need to parse smaps instead of just maps? I.e. in my >>> system, a desktop one, F21, I have: >>> >> >> It seems no other info tell us if one process is using hugetlbfs. >> So how about an option to tell perf explicitly which file is from >> hugetlbfs, like: >> >> ./perf report --hugetlb-file=/mnt/huge/hugepagefile >> >> So that, we can check if a mmap area is from hugetlbfs by its name >> instead of MAP_HUGETLB. > > Well, we _can_ detect this automatically, its just a matter of parsing > /proc/PID/smaps, right? > > What I was discussing was a way only parse smaps when we know we need > to, i.e. when we, for instance, parsing /proc/PID/maps, find a map that > we think may be a hugetlb one, maybe some other way to tell us that > hugetlb maps are in place, looking at the hugetlbfs stats somehow? >
Another solution, we can parse /proc/self/mounts. Here is the /proc/self/mounts in my system:
..... /dev/root / ext2 rw,relatime,errors=remount-ro 0 0 tracefs /sys/kernel/debug/tracing tracefs rw,relatime 0 0 nodev /mnt/huge hugetlbfs rw,relatime 0 0 ....
from /proc/self/mounts, we can get mount point of hugetlbfs. in my system, it is "/mnt/huge". So that, when mmap2 event comes from userspace, we can compare prefix of filename with hugetlbfs mount point (e.g "/mnt/huge") to check if it is a file in hugetlbfs. if it is, set MAP_HUGELTB, otherwise, not set.
There is no need to parse /proc/PID/smaps now, what's more, it is not difficult to parse "/proc/self/mounts".
> - Arnaldo > > . >
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