I looked at THP before. It comes enabled on RHEL6 and on our KVM hosts it merges a lot (~300GB hugepages on a 400GB KVM footprint). I am probably going to disable it and see if it introduces any problems for me - the most important gain here is better processor memory lookup table (cache) utilization where it considerably lowers the number of entries. Not sure how it affects different workloads - HPC guys should have a good idea? I can only evaluate the effect on OSDs and KVM, but the problem is that going over the cache limit even by a tiny bit can have huge impact - theoretically... This issue sounds strange, though. THP should kick in and defrag/remerge the pages that are part-empty. Maybe it's just not aggressive enough? Does the "free" memory show as used (part of RSS of the process using the page)? I guess not because there might be more processes with memory in the same hugepage. This might actually partially explain the pagecache problem I mentioned there about a week ago (slow OSD startup), maybe kswapd is what has to do the work and defrag the pages when memory pressure is high! I'll try to test it somehow, hopefully then there will be cake. Jan > On 09 Sep 2015, at 07:08, Alexandre DERUMIER <aderumier@xxxxxxxxx> wrote: > > They are a tracker here > > https://github.com/jemalloc/jemalloc/issues/243 > "Improve interaction with transparent huge pages" > > > > ----- Mail original ----- > De: "aderumier" <aderumier@xxxxxxxxx> > À: "Sage Weil" <sweil@xxxxxxxxxx> > Cc: "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx>, "ceph-users" <ceph-users@xxxxxxxxxxxxxx> > Envoyé: Mercredi 9 Septembre 2015 06:37:22 > Objet: Re: jemalloc and transparent hugepage > >>> Is this something we can set with mallctl[1] at startup? > > I don't think it's possible. > > TP hugepage are managed by kernel, not jemalloc. > > (but a simple "echo never > /sys/kernel/mm/transparent_hugepage/enabled" in init script is enough) > > ----- Mail original ----- > De: "Sage Weil" <sweil@xxxxxxxxxx> > À: "aderumier" <aderumier@xxxxxxxxx> > Cc: "Mark Nelson" <mnelson@xxxxxxxxxx>, "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx>, "ceph-users" <ceph-users@xxxxxxxxxxxxxx>, "Somnath Roy" <somnath.roy@xxxxxxxxxxx> > Envoyé: Mercredi 9 Septembre 2015 04:07:59 > Objet: Re: jemalloc and transparent hugepage > > On Wed, 9 Sep 2015, Alexandre DERUMIER wrote: >>>> Have you noticed any performance difference with tp=never? >> >> No difference. >> >> I think hugepage could speedup big memory sets like 100-200GB, but for >> 1-2GB they are no noticable difference. > > Is this something we can set with mallctl[1] at startup? > > sage > > [1] http://www.canonware.com/download/jemalloc/jemalloc-latest/doc/jemalloc.html > >> >> >> >> >> >> >> ----- Mail original ----- >> De: "Mark Nelson" <mnelson@xxxxxxxxxx> >> À: "aderumier" <aderumier@xxxxxxxxx>, "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx>, "ceph-users" <ceph-users@xxxxxxxxxxxxxx> >> Cc: "Somnath Roy" <somnath.roy@xxxxxxxxxxx> >> Envoyé: Mercredi 9 Septembre 2015 01:49:35 >> Objet: Re: jemalloc and transparent hugepage >> >> Excellent investigation Alexandre! Have you noticed any performance >> difference with tp=never? >> >> Mark >> >> On 09/08/2015 06:33 PM, Alexandre DERUMIER wrote: >>> I have done small benchmark with tcmalloc and jemalloc, transparent hugepage=always|never. >>> >>> for tcmalloc, they are no difference. >>> but for jemalloc, the difference is huge (around 25% lower with tp=never). >>> >>> jemmaloc 4.6.0+tp=never vs tcmalloc use 10% more RSS memory >>> >>> jemmaloc 4.0+tp=never almost use same RSS memory than tcmalloc ! >>> >>> >>> I don't have monitored memory usage in recovery, but I think it should help too. >>> >>> >>> >>> >>> tcmalloc 2.1 tp=always >>> ------------------- >>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND >>> >>> root 67746 120 1.0 1531220 671152 ? Ssl 01:18 0:43 /usr/bin/ceph-osd --cluster=ceph -i 0 -f >>> root 67764 144 1.0 1570256 711232 ? Ssl 01:18 0:51 /usr/bin/ceph-osd --cluster=ceph -i 1 -f >>> >>> root 68363 220 0.9 1522292 655888 ? Ssl 01:19 0:46 /usr/bin/ceph-osd --cluster=ceph -i 0 -f >>> root 68381 261 1.0 1563396 702500 ? Ssl 01:19 0:55 /usr/bin/ceph-osd --cluster=ceph -i 1 -f >>> >>> root 68963 228 1.0 1519240 666196 ? Ssl 01:20 0:31 /usr/bin/ceph-osd --cluster=ceph -i 0 -f >>> root 68981 268 1.0 1564452 694352 ? Ssl 01:20 0:37 /usr/bin/ceph-osd --cluster=ceph -i 1 -f >>> >>> >>> >>> tcmalloc 2.1 tp=never >>> ----------------- >>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND >>> >>> root 69560 144 1.0 1544968 677584 ? Ssl 01:21 0:20 /usr/bin/ceph-osd --cluster=ceph -i 0 -f >>> root 69578 167 1.0 1568620 704456 ? Ssl 01:21 0:23 /usr/bin/ceph-osd --cluster=ceph -i 1 -f >>> >>> >>> root 70156 164 0.9 1519680 649776 ? Ssl 01:21 0:16 /usr/bin/ceph-osd --cluster=ceph -i 0 -f >>> root 70174 214 1.0 1559772 692828 ? Ssl 01:21 0:19 /usr/bin/ceph-osd --cluster=ceph -i 1 -f >>> >>> root 70757 202 0.9 1520376 650572 ? Ssl 01:22 0:20 /usr/bin/ceph-osd --cluster=ceph -i 0 -f >>> root 70775 236 1.0 1560644 694088 ? Ssl 01:22 0:23 /usr/bin/ceph-osd --cluster=ceph -i 1 -f >>> >>> >>> >>> jemalloc 3.6 tp = always >>> ------------------------ >>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND >>> >>> root 92005 46.1 1.4 2033864 967512 ? Ssl 01:00 0:04 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> root 92027 45.5 1.4 2021624 963536 ? Ssl 01:00 0:04 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> >>> >>> >>> root 92703 191 1.5 2138724 1002376 ? Ssl 01:02 1:16 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> root 92721 183 1.5 2126228 986448 ? Ssl 01:02 1:13 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> >>> >>> root 93366 258 1.4 2139052 984132 ? Ssl 01:03 1:09 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> root 93384 250 1.5 2126244 990348 ? Ssl 01:03 1:07 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> >>> >>> >>> jemalloc 3.6 tp = never >>> ----------------------- >>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND >>> >>> root 93990 238 1.1 2105812 762628 ? Ssl 01:04 1:16 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> root 94033 263 1.1 2118288 781768 ? Ssl 01:04 1:18 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> >>> >>> root 94656 266 1.1 2139096 781392 ? Ssl 01:05 0:58 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> root 94674 257 1.1 2126316 760632 ? Ssl 01:05 0:56 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> >>> root 95317 297 1.1 2135044 780532 ? Ssl 01:06 0:35 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> root 95335 284 1.1 2112016 760972 ? Ssl 01:06 0:34 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> >>> >>> >>> jemalloc 4.0 tp = always >>> ------------------------ >>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND >>> >>> root 100275 198 1.3 1784520 880288 ? Ssl 01:14 0:45 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> root 100320 239 1.1 1793184 760824 ? Ssl 01:14 0:47 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> >>> >>> root 100897 200 1.3 1765780 891256 ? Ssl 01:15 0:50 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> root 100942 245 1.1 1817436 746956 ? Ssl 01:15 0:53 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> >>> root 101517 196 1.3 1769904 877132 ? Ssl 01:16 0:33 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> root 101562 258 1.1 1805172 746532 ? Ssl 01:16 0:36 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> >>> >>> jemalloc 4.0 tp = never >>> ----------------------- >>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND >>> >>> root 98362 87.8 1.0 1841748 678848 ? Ssl 01:10 0:53 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> root 98405 97.0 1.0 1846328 699620 ? Ssl 01:10 0:56 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> >>> >>> >>> root 99018 233 1.0 1812580 698848 ? Ssl 01:12 0:30 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> root 99036 226 1.0 1822344 677420 ? Ssl 01:12 0:29 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> >>> root 99666 281 1.0 1814640 696420 ? Ssl 01:13 0:33 /usr/bin/ceph-osd --cluster=ceph -i 5 -f >>> root 99684 266 1.0 1835676 676768 ? Ssl 01:13 0:32 /usr/bin/ceph-osd --cluster=ceph -i 4 -f >>> >>> >>> >>> >>> ----- Mail original ----- >>> De: "aderumier" <aderumier@xxxxxxxxx> >>> À: "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx>, "ceph-users" <ceph-users@xxxxxxxxxxxxxx> >>> Envoyé: Mardi 8 Septembre 2015 21:42:35 >>> Objet: jemalloc and transparent hugepage >>> >>> Hi, >>> I have found an interesting article about jemalloc and transparent hugepages >>> >>> https://www.digitalocean.com/company/blog/transparent-huge-pages-and-alternative-memory-allocators/ >>> >>> >>> Could be great to see if disable transparent hugepage help to have lower jemalloc memory usage. >>> >>> >>> Regards, >>> >>> Alexandre >>> >>> _______________________________________________ >>> ceph-users mailing list >>> ceph-users@xxxxxxxxxxxxxx >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>> -- >>> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >> -- >> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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