Re: how to debug slow rbd block device

[Stefan Priebe - Profihost AG <s.priebe@profihost.ag>]

Am 23.05.2012 09:22, schrieb Andrey Korolyov:
> Hi,
> 
> For Stefan:
> 
> Increasing socket memory gave me about some percents on fio tests
> inside VM(I have measured
> 'max-iops-until-ceph-throws-message-about-delayed-write' parameter).
> What is more important, osd process, if possible, should be pinned to
> dedicated core or two, and all other processes should not use this
> core(you may do it via cg or manually), because even one four-core
> non-pinned VM process during test causes a drop of osd` throughput
> almost twice, same for any other heavy process on the host.
Tried that using taskset but i didn't get any noticable boost. Also the
kernel already prevents jumping from core 2 core whenever possible. As
these machines are dedicated to osd there is no other load.

> net.core.rmem_max = 16777216
> net.core.wmem_max = 16777216
> net.ipv4.tcp_rmem = 4096 87380 16777216
> net.ipv4.tcp_wmem = 4096 65536 16777216
This gaves me around 3-4 MB/s.

Stefan