[gentoo-amd64] Re: Re: Tcp transfer has a pause every few seconds

[Duncan]

P.V.Anthony posted <4364E65D.4070109@×××××××××××.sg>, excerpted below,  on
Sun, 30 Oct 2005 23:27:25 +0800:

> specs and observations.
>
> Specs.
> cpu: AMD 64 3000+
> drives: Sata drives
> mobo: MSI Neo 4 Platinum
> Ram: 2GB
> Raid: Promise EX8350
> OS: Gentoo
> Kernel: 2.6.13 r3
> Filesystem: XFS

Now that I see that mobo listed...

See the other threads currently active on the list/group right now.  (You
can read the list as either a newsgroup or a web forum, thru gmane.org.  I
use their list2news interface to read the list as a newsgroup.  That way
you can see posts from before you subscribed, if desired.)  

I haven't kept exact track but it seems I'm seeing that mobo mentioned in
three different active threads ATM, this one included.  The latest BIOS
(1.B IIRC?) apparently has some rather major issues with recent kernels.
The threads have been saying either revert to 1.9 (or whatever it was) or
try an earlier kernel (2.6.11 or earlier, IIRC).  They problems mentioned
haven't been this one, but it's a troublesome combination in any case, so
certainly read up, and consider reverting either the kernel or the BIOS.

NOTE THAT ONE GUY ENDED UP FRYING HIS BIOS REVERTING, and had to buy a new
chip ($10-ish, but he had to wait for it to be delivered).  However, he
was having issues getting into the BIOS already (the keyboard wasn't being
activated soon enough to detect the delete to put it in BIOS edit mode),
and it's possible the fried BIOS was related to that.

The $10 isn't bad, so you might wish to order the spare BIOS chip and have
it on hand before you try reverting, just in case.

...  As I said in a different thread, altho I understand it's changed a
bit now, back when I was shopping for my dual Opteron board, it was
between a Tyan and an MSI board.  Visiting the MSI site, all their BIOS
upgrades AND all their documentation was in MSWormOS executable format
(I'm guessing self-extracting zip, but all I know is it had the .exe at
the end).  Tyan had the more traditional pdf docs and zip file BIOS packs.
I emailed MSI and told them why they lost the sale.  (The MSI board was
cheaper and I would have likely gotten it if it looked like they cared at
all about their Linux customers.)  Maybe my mail was  part of what made
them decide to switch back to normal formats.  

Anyway, I've been quite impressed with Tyan -- they are quite responsive
on the Linux front and regularly have Linux drivers, and even have
customized lm_sensors configs for their boards.  As well, many of them
carry Linux certifications -- the manual for mine says Red Hat, SuSE, and
Turbo Linux, all three, supported and certified.

MSI OTOH, as I explained, I was rather disimpressed with, and the recent
threads here on the list haven't helped.  I consider myself lucky to have
gone Tyan, and don't think I'll be considering MSI any time soon.

> Observations.
> When I was using the xfs I had the problem of the pauses in the tcp
> transfers. These pauses, I am guessing is because of the pdflush that
> occurs around every 20 seconds. There is only one pdflush every 20
> seconds. This caused lose of video frames when we did the video recording.
> The video would have a jerk or jump when played back.
>
> I changed the dirty_ratio from the default of 40 to 5. This solved the
> problem. During the recording preview there seems to be some jerks but
> during the playback it seems to be ok. The pdflush happens more often and
> there is still one pdflush. I think the jerk that I see in the record
> preview coincides with the pdflush. More jerks in record preview but ok
> during playback.
>
> Next I formatted the drives to the ext3 filesystem. The dirty_ratio was
> set back to the default value of 40. When the video started to record
> there is no loss of frames and no jerks in the preview window. During the
> playback there is no loss. Everything is good. Check the top for pdflush
> and noticed that the there is two pdflush. The pdflushs is happening at
> every 5 seconds or so. Very fast compared to when I was using xfs.
>
> So the problem must be my xfs setting. For xfs I have only used the
> default setting. Or could there be a problem with xfs and AMD64 kernel?
>
> What must I do to get xfs to work? Or what am I doing wrong?

The dirty_ratio stuff you mention is beyond my level -- you know more
there than I do by far, it would seem.  I've only used reiserfs here,
since I switched to Linux, as well, so can't say much about ext2/3 or xfs,
beyond what's out there to read about them.  I /can/ say I have two
pdflush threads here, but I always figured that was one running on each
CPU...

Anyway, now that you mentioned the MSI Neo 4 Platinum mobo, with the other
threads on it, I'd say the BIOS/kernel issues from that very likely are
causing your issues as well.  Address that, and there's a good chance your
problems will disappear.  In any case, there are several others on the
list with that board to compare notes with, which should help.

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman in
http://www.linuxdevcenter.com/pub/a/linux/2004/12/22/rms_interview.html


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