Re: 2.1.114 VFS code 5x slower than 2.0.33?!?
Michel Catudal (bbcat@netonecom.net)
Fri, 07 Aug 1998 13:02:45 -0400
Zlatko Calusic wrote:
>
> I don't know if others noticed, but deleting files in 2.1.x kernels
> seems way too slow. I decided to make a benchmark today, and come to a
> surprising results. All test were made on the same machine, unloaded
> and with lots of free RAM (P166MMX, 64MB RAM, IDE disk).
>
> First I made lots of files/directories with this (quite stupid)
> script:
>
> time zsh -c 'while ((a < 10000))
> do
> x="$RANDOM/$RANDOM"
> mkdir -p $x
> : >! $x/$RANDOM
> ((a = a + 1))
> done'
>
> After that I first timed 'ls -al':
>
> {2.0.33} [/tmp/foodir]% time ls -al | wc -l
> 1.20user 0.96sys 0:02.19real 98%CPU (125major+513minor)pagefaults 0swaps
> 8618
>
> {2.1.114} [/tmp/foodir]% time ls -al | wc -l
> 1.25user 6.30sys 0:07.56real 99%CPU (125major+511minor)pagefaults 0swaps
> 8578
>
> 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.
>
> Then I tested deleting all those files, and results were similarly bad
> for 2.1.x. This time, 2.1 spent slightly less time in kernel, but
> overall still was almost 6 times slower:
>
> {2.0.33} [/tmp/foodir]% time rm -rf *
> 1.50user 33.35sys 1:30.74real 38%CPU (81major+20minor)pagefaults 0swaps
>
> {2.1.114} [/tmp/foodir]% time rm -rf *
> 1.34user 21.42sys 7:13.88real 5%CPU (84major+20minor)pagefaults 0swaps
>
> 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.
>
> Anybody care to shed some light on this?
>
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?
--
Tired of Windows' rebootive multitasking?
then try Linux's preemptive multitasking
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