Re: Kernel 2.2.19 crashes, 2.4.4 bad performance
On Tue, 15 May 2001, T. Weyergraf wrote:
> Reworked is good - it's rather a total rewrite ;-) The VM is one of my suspects, but
> I also question the new scheduling policies.
> As all UP2000's being EV-67 ( or 68 ), mine is a EV-67, 667Mhz and 2Mbytes L2.
> The system comes with 1.5Gig RAM, which should ( and does ) ensure, that swap
> isn't reached.
True, but I've seen stranger things happen :-)
> Good, i'll try that. I obviously have CONFIG_RTC set. On that issue: It used to be the
> case, that the Alphas encountered clock-skews without that option set in earlier 2.2 kernels,
> that could be overcome by setting RTC. Is that resolved ? Having the correct time is
> quite critical in my setup ( time-based services running across several NFS exports ).
I would recommend running an NTP daemon or something to sync the time on
all of your servers on boot and periodically rather than relying on the
RTC. It tends to be more reliable when you're dealing with multiple
servers anyway (rather than having to set time that's fairly close on
multiple machines by hand).
> It's 3 adaptecs in there, plus one 3COM networking card ( 905B ). I've seperately ran
> tests on all harddrives, using bonnie, hdparm and my own stuff. All results indicated no
> difference in drive performance and associated CPU consumption. All disks are in fact
> SCSI disks. I had one IDE drive with an SCSI-to-IDE adaptor being connected to it;s
> own adaptec ( since it can't do TCQ ), but that was completely disabled during the tests.
> I am aware, that there is a completely new aic driver in 2.4.4, which gave the reason
> to test disk performance.
> I do like the fact, that the new driver is apparently able to determine the optimum TCQ depth
> during run-time. However, i prefer to set things via boot-parameters. Anybody ever
> figured out, how to do that with the new driver ?
I haven't looked at it too hard yet. I personally like the old driver
better, but that's only because I'm more familiar with it code-wise :-P
Was there much net traffic when you ran the tests or was the 3Com mostly
inactive?
> On the issue of the performance difference, i have had tests, that measure process CPU
> consumption with both, times(2) and getrusage(2). The ones with getrusage(2) show
> strange behaviour, by giving user-times on kernel 2.2.19, that are questionable.
>
> Has anybody ever found evidence, that getrusage() reports strange user-times ?
> The most bizarre thing is, that real- as well as system time seem OK, as well as times(2) times ;-)
Not yet. I'll see if I can free up some time to look at it more
in-depth. Sounds like you definitely have a strange case,
though. Perhaps I'll run some tests on my UP2k at work over the coming
weekend and see if I get similar results.
C
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