Re: Linux SMP
On Mon, 31 Aug 1998, Philip Thiem wrote:
> I'm wonder, and perhap some you linux buffs could help.
> HOw great is the performance gain from SMP? I have been debating this
> with a friend. I know linux has muli-threaded capability, but like the
> kernal isn't explicitly multithreaded(or is it), yeah you can compile it
> for multiple processors, and the same with other application without
> explicitly using the threads library, sort of creating multiple
> processes.. Are these process indpendent of each other in a way that a
> noticable benefit would be gained from SMP. I'm new to the detail of
> SMP so any information would be nice
>
> Thanks
>
> Philip Thiem
> ptt@umr.edu
According to Linus, the SMP performance of the 2.0 kernels is not all that
great. About comparable to NT. The next kernel version will be a lot
better due to finer granularity of kernel locks.
How much performance gain you get will depend on what you are doing. If
your are doing a lot in user space, such as compiling kernels, the
performance boost is pretty good. If you are doing a lot in kernel space,
like serving web pages (go to disk, get data, move it to the network) you
will not see much performance boost at all.
Alan Cox has been backporting some of the 2.1 improvements into 2.0 but I
am not sure how much he can really do considering the basic layout of 2.0.
SMP has been one of the things that Linus himself has been concentrating
on according to a talk he gave at SVLUG this spring.
The earlier kernels just had a lot of deadlock and race conditions. It
would be perfectly natural for a 2.0.x SMP box to simply hang under heavy
load. The word is that the current 2.1 kernels are much better. 2.0 is
really out of date.
Since 2.1 is officially frozen except for bugfixes, it might be nice for
someone to start making kernel images available in project. We can help
test some of this code. I am not saying to make an image of every 2.1
kernel but there are a few that come along from time to time that are
exceptionally stable. It looks like the NFS bugs are getting nailed down
in the most recent releases so maybe it is time.
George Bonser
The Linux "We're never going out of business" sale at an FTP site near you!
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