Messages in this thread | | | Date | Wed, 25 Jun 2008 08:18:37 +0200 | Subject | Re: [RFC -mm 0/6] sysv ipc: scale msgmnb with the number of cpus | From | Solofo.Ramangalahy@bull ... |
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Manfred Spraul writes: > > Humm... now this make me think that you did not change the MSGMNB > > value when you changed MSGMNI and MSGMAX. > > Maybe that was on purpose? > > > > > I was afraid that it might break user space applications that queue a > few kb of messages.
Ok, the choice of a maximum value of 65536 which is already is use for several months/years was made partly for the same concern. Beside, as the values are not enforced, we should be relatively safe.
Searching the archives, I also found usage of a value "around a MB".
> That's also the reason for > > if (msgsz + msq->q_cbytes <= msq->q_qbytes && > > 1 + msq->q_qnum <= msq->q_qbytes) { > > break; > > } > It's possible to send 0-byte messages even if the message queue is full > [except that you can't send more than MSGMNB messages].
Thanks for this information. I should add that I checked that no regression was introduced with ltp-full-20080531, but I did not look more closely (e.g. coverage of this part of the code).
-- solofo
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