[DRBD-user] Page allocation failure (IPOIB, Infiniband, connected mode)

Florian Haas florian at hastexo.com
Fri Mar 16 13:55:17 CET 2012

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Wed, Mar 14, 2012 at 7:48 AM, Christian Balzer <chibi at gol.com> wrote:
> Hello,
> This is basically a repeat of:
> http://lists.linbit.com/pipermail/drbd-user/2011-August/016758.html
> 32GB RAM, Debian Squeeze, 3.2 (debian backport) kernel, 8.3.12 DRBD,
> IPOIB in connected mode with a 64k MTU. Just 2 DRBD resources.
> After encountering this for the first time (never showed up in two weeks
> of stress testing, which only goes to prove that real life just can't be
> simulated) I found the above article and changed the following sysctls:
> vm/min_free_kbytes = 262144
> net.core.rmem_max = 16777216
> net.core.wmem_max = 16777216
> net.ipv4.tcp_rmem = 65536 87380 16777216
> net.ipv4.tcp_wmem = 65536 65536 16777216
> net/ipv4/tcp_mem is by default at "775464  1033954 1550928" which should be
> plentiful.
> After the changes I disconnected and reconnected the resources, thus hopefully applying those changes to the actual links.
> And initially I couldn't reproduce the problem, but it showed up again last
> night.
> Lars hinted at "atomic reserves" in his reply, which particular parameters
> are we talking about here?

I had hoped for Lars to pitch in here, but I guess I'll give it a go
instead. Note I'm certainly no kernel memory management expert, but
I'm not aware of anything that would fit that description other than
the vm.min_free_kbytes sysctl you've already mentioned.

SUSE's kernel documentation team, btw, lists these "page allocation
failure" warnings as no cause for concern as long as they happen


I realize this may not help much, but perhaps it helps a little. :)


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