Hm, interesting suggestion. But didn't change anything. :( Thanks anyway, Jérémie 2012/9/26 Adrian Sevcenco <Adrian.Sevcenco at cern.ch>: > On 09/26/12 19:14, Jérémie Dubois-Lacoste wrote: >> >> Dear All, > > Hi! > > >> We recently reinstalled our computing cluster. We were using CentOS >> 5.3 (32 bits). It is now CentOS 6.3 (64 bits), installed from the >> CentOS 6.2 x64 CD, then upgraded to 6.3. >> >> We have some issues with the memory needs of our running jobs. They >> require much more than before, it may be due to the switch from 32 to >> 64 bits, but to me this cannot explain the whole difference. > > it would seem that there is a malloc(glibc) behaviour ... > i seen in other list an advice to use : > export MALLOC_ARENA_MAX=1 > export MALLOC_MMAP_THRESHOLD=131072 > > in order to decrease the used memory .. > > HTH, > Adrian > >> >> Here are our investigations. >> >> We used the following simple benchmark: >> >> 1. Run a python script and check the memory that >> it requires (field "VIRT" of the "top" command). >> This script is: >> ---- >> import time >> time.sleep(30) >> print("done") >> ---- >> >> 2. Similarly, run and check the memory of a simple >> bash script: >> ---- >> #!/bin/bash >> sleep 30 >> echo "done" >> ---- >> >> 3. Open a R session and check the memory used >> >> >> I asked 10 of our users to run these three things on their personal >> PCs. They are running different distributions (mainly ubuntu, >> slackware), half of them use a 32 bits system, the other half a 64 >> one. Here is a summary of the results: >> >> Bash script: >> Avg Min Max >> 32 bits 5400 4192 9024 >> 64 bits 12900 10000 16528 >> >> Python script: >> Avg Min Max >> 32 bits 8500 5004 11132 >> 64 bits 32800 30000 36336 >> >> R: >> Avg Min Max >> 32 bits 26900 21000 33452 >> 64 bits 100200 93008 97496 >> >> (as a side remark, the difference between 32 and 64 is surprisingly >> big to me...). >> >> Then we ran the same things on our CentOS cluster, getting >> surprisingly high results. I installed a machine from scratch with the >> CentOS CD (6.2 x64) to be sure another component of the cluster was >> not playing a role. On this freshly installed machine I get the >> following results: >> SH: 103MB >> PYTHON: 114MB >> R: 200MB >> >> So, compared to the highest of our users (among the 64 bits ones), we >> have a ratio of ~7, ~3, ~2, respectively. >> >> >> It is very problematic for us because many jobs now cannot run >> properly, because they lack memory on most of our computing nodes. >> So we really cannot stand the situation... >> >> Do you see any reason for this? Do you have suggestions? >> >> Sincerely, >> >> Jérémie >> _______________________________________________ >> CentOS mailing list >> CentOS at centos.org >> http://lists.centos.org/mailman/listinfo/centos >> > > > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos >