Messages in this thread | | | From | KOSAKI Motohiro <> | Date | Tue, 1 Apr 2014 16:15:14 -0400 | Subject | Re: [PATCH] ipc,shm: increase default size for shmmax |
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>> Our middleware engineers has been complaining about this sysctl limit. >> System administrator need to calculate required sysctl value by making sum >> of all planned middlewares, and middleware provider needs to write "please >> calculate systcl param by....." in their installation manuals. > > Why aren't people just setting the sysctl to a petabyte? What problems > would that lead to?
I don't have much Fujitsu middleware knowledges. But I'd like to explain very funny bug I saw.
1. middleware-A suggest to set SHMMAX to very large value (maybe LONG_MAX, but my memory was flushed) 2. middleware-B suggest to set SHMMAX to increase some dozen mega byte.
Finally, it was overflow and didn't work at all.
Let's demonstrate.
# echo 18446744073709551615 > /proc/sys/kernel/shmmax # cat /proc/sys/kernel/shmmax 18446744073709551615 # echo 18446744073709551616 > /proc/sys/kernel/shmmax # cat /proc/sys/kernel/shmmax 0
That's why many open source software continue the silly game. But again, I don't have knowledge about Fujitsu middleware. I'm waiting kamezawa-san's answer.
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