implications of SMP kernel on UP
helge.oldach at atosorigin.com
Fri Apr 2 04:25:39 PST 2004
>Le Thursday 01 April 2004 09:10, Bjoern A. Zeeb a écrit :
>> what are the implications on running an SMP enabled kernel on a UP
>> machine ?
>> I first thought of things like:
>> - performence (most likely not worth the discussion ?)
>I got an improvement with a factor of ten between an SMP and a UP
>kernel on a HTT-enabled P4/2,6GHz/800MHz FSB on network transfers (with
>gigabit Ethernet boards: SMP gives about 6MB/s for FTP transfer rate,
>and UP gives up to 75MB/s)
>So: as long as the network stack is not fully locked (this is coming -
>perhaps for 5.3), a server should definitely run a UP kernel.
Ooops, that is indeed dramatic.
Does the same locking impact also affect other, interrupt-bound
subsystems, such as the disk subsystem (in particular SCSI)?
I am asking because I have a HTT machine that walks some 35.000
files every few minutes with an aggreated disk I/O load of only 5
MBytes/second, while the SCSI hardware is able to do SCSI-3/160...
It appears that a lot of processes are indeed disk bound ("D").
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