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SubjectRe: What version of the kernel fixes these VM issues?
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On August 25, 2001 05:00 am, Nicolas Pitre wrote:
> This board has 32MB RAM, no swap. Root fs is NFS. On the serial console I
> start a command line mp3 player. In a first telnet session I start a build
> of gcc 3.0 (./configure; make). In a second telnet session I start 'top'.
> Music plays while gcc builds and I can see the CPU usage within top.
> Pretty real scenario, real life situation, expected system load, no trick.

You're streaming the mp3 over nfs, right? From your setup I'd guess there's
no local hard disk.

> nfs: task 41867 can't get a request slot
> nfs: task 41868 can't get a request slot
> nfs: task 41869 can't get a request slot

Uhuh. Would you please look in your logs for "allocation failed" messages?
(Side note: reading the nfs code now... to whose eyes are names like tk_rqstp
beautiful?)

> ( Active: 2007, inactive_dirty: 0, inactive_clean: 0, free: 253 (255 510
765) )

Whoops, nothing inactive but kswap going full blast. We're getting warmer.

> 2.4.9 kernel:
> =============
>
> Unlike the first (quoted) run, this kernel completely stalled when the jam
> conditions were reached just like the run described above. I mean here
> there is no audio stuttering at all, no echo from telnet sessions, nothing
> in user space gets to run anymore.

Yes, a slight difference, however they are both wedged in the same way, from
your task samples:

> PC value System.map
> -------- ----------
> c003f6e0 zone_inactive_plenty
> c003fa58 swap_out_pmd
> c0060324 prune_icache
> c003f6fc zone_inactive_plenty
> c003faac swap_out_pmd
> c00209a0 cpu_sa1100_set_pte
> c003fc80 swap_out_mm
> c0040c10 refill_inactive_scan
> c00206c0 cpu_sa1100_cache_clean_invalidate_range
> c003fa90 swap_out_pmd

> Kernel interrupts and BHs still work i.e. I can ping the box, the serial
> console still echoes characters (kernel termios), and sysrq works but that's
> all. What's also interesting here is the fact that there is absolutely no
> NFS traffic going on.

That's understandable. Everything that needs to allocate memory is wedged.

> - The same behavior occurs with 2.4.8-ac4.

How far back do you have to go before you get one that works? I seem to
recall the inactive_plenty changes came in at 2.4.8-pre1. Could you try it
with 2.4.7, please.

--
Daniel
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