I did some more checking, per "Linux NFS and Automounter Administration",
the queue is split between all the NFS server threads. So the default 64k
is split between the 8 default threads, 8k per thread.
So some of this seems to be confusion between what is a thread and what is a
daemon; per Kabir's book, we are starting 8 daemons by default, and each
daemon gets its own queue. Per Craig Hunt, we are starting 8 threads by
default, and the queue is split between the threads of a single daemon.
As David points out, there's a huge difference in the two semantic points,
especially for those of us running hundreds of threads.
Anyone know for sure? Any quick and dirty tests to prove this to ourselves?
> From: David Dougall [mailto:[email protected]]
> Subject: Re: [NFS] RedHat 8.0 nfs
>
> This doesn't agree with what I have heard before. I was always told that
> this memory amount( 256k default) was shared by all threads. Therefore
> the more threads you had, the more contention for memory, less each thread
> had, etc. You are now saying that each thread gets its own amount.
> Which one is correct. This drastically affects the number of threads and
> the value that I assign in this parameter.
> Anyone who authoritatively knows, please advise.
> --David Dougall
>
>On Mon, 24 Mar 2003, [email protected] wrote:
>>
>>>>Also, what would be a good number for NFS_QS? Both rmem.default and
>>>>rmem.max will be set to this number; should it be a multiple of threads?
>>>>Say something like smallest binary power (2^n) greater than 1500 (MTU
>>size) >>* $RPCNFSDCOUNT
>>
>>> Again this dependent on how much memory you have...
>>
>>I was reviewing this topic in "Red Hat Linux Security & Optimization", it
>> claims that each nfsd daemon will receive a queue of size NFS_QS, so I
>> assume the above concerns aren't relevant. (aside from memory concerns,
>> using 256kb * 200 threads/daemon = 50Mb for input queues :^)
>>
>>As a side note, with the new RH scripts upping the queue size,and revamped
>>client mount scripts upping the rsize/wsize, thread utilization seems tobe
>>way down and performance up
>>
>>Th 120 5652 4721.126 892.199 136.818 25.683 5.923 2.136 1.755 1.833 1.689
>>3.267
>>
>>In the past my 100% numbers would have spiked sharply upwards (And this is
>>with a recompiled official RedHat kernel, not the known faster 2.4.20
>>kernel). 'Course, its also with a new core system, running Dual 1.3Ghz cpu
>>instead of Dual 667Mhz; but the IO is pretty much the same, a FC attached
>>IBM ESS Shark. But I expect that the CPU's aren't a huge factor, since the
>>old system never went above about 60% utilization in a pure nfs mode.
>>
>>So all in all, life is good. Thanks for the help.
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