[ClusterLabs] PCMK_ipc_buffer recommendation

Jan Pokorný jpokorny at redhat.com
Tue Jan 22 09:19:03 EST 2019


On 21/01/19 16:38 -0600, Ken Gaillot wrote:
> On Sat, 2019-01-19 at 00:46 +0200, Michael Kolomiets wrote:
> I wish there were a convenient formula,

part of this non-straightforward evaluation is fact that some daemons
connect to other local "mates" only intermittently, on an ad-hoc basis,
if my recollection is correct.

> but all we have now is the log messages that say when it's too
> small. It's generally correlated to the size of the CIB.

On 18/01/19 10:24 -0600, Ken Gaillot wrote:
> On Fri, 2019-01-18 at 08:22 +0100, Ferenc Wágner wrote:
>> Growing 10 MB would be OK, growing 10 MB * some biggish number
>> wouldn't.
> 
> Each daemon will need 10MB per active client. The number of clients
> is unlikely to grow large in normal operation (maybe a dozen or
> so?), though one could imagine a runaway loop in some script
> spawning a bunch of commands that need client connections, or 100
> resource monitors all setting node attributes at the same time.
> 
> The OS never reclaims memory from a process, so once a daemon
> balloons to a certain size, it will never be smaller (even if it
> frees memory, that will just go back into its own available pool).

This likely conflates virtual address space and really consumed pages
of physical memory at given point on process' lifeline, otherwise the
casual computing would be a sad experience with long running processes,
even with today's memory sizes (not to speak about constrained consumer
electronic devices).

-- 
Jan (Poki)
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