Re: 2.1.114 VFS code 5x slower than 2.0.33?!?

Alan Cox (alan@lxorguk.ukuu.org.uk)
Sat, 8 Aug 1998 01:20:43 +0100 (BST)


---------Case 1---------

> > Notice how 2.1.114 spends much more time in the kernel (6 times more
> > than 2.0.33). Overall it is 3 times slower.

Thats the dcache I suspect. Its probably a win for most uses however.
You can use the kernel profiling to find out. Also remember to compare
non SMP kernels with non SMP kernels

> > If I'm right, this implies that 2.1.114 is very bad for proxy and/or
> > news servers, who both operate on lots of files, creating/deleting
> > them at fast rate.

Proxies spend most of their time looking up files. I wouldnt expect that
to be this worst case you report

> > Anybody care to shed some light on this?

Can you see if 2.1.115ac1 is any better on this benchmark on your box

---------Case 2----------

> Having a 486 and not the fastest disk in the world I have noticed it
> very
> easily. It took over 1 hours to download 232 files at a modem speed
> of 28800. The same thing takes less than a fourth of that with kernel
> 34. I was using kernel 113 not 114 but they're quite close.
> Is it some debug code that is slowing the whole thing down or some
> Microsoft programmer got on board?

Do you have SMP enabled, does it have 16450 UARTS, do you have hdparm -u1 set

[Im guessing you are seeing serial overruns]

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