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SubjectRe: What version of the kernel fixes these VM issues?
 --- Nicolas Pitre <nico@cam.org> wrote: > 
> On Sat, 25 Aug 2001, Daniel Phillips wrote:
>
> > On August 24, 2001 10:12 pm, Nicolas Pitre wrote:
> > > On Fri, 24 Aug 2001, Daniel Phillips wrote:
> > >
> > > > On August 24, 2001 08:14 pm, Nicolas Pitre
> wrote:
> > > > > I have a totally different setup but I can
> reproduce the same behavior on
> > > > > the system I have here:
> > > > >
> > > > > ARM board with 32 MB RAM, no cache, NFS
> root.
> > > > > The kernel is based on 2.4.8-ac9 plus some
> small VM fixes from -ac10.
> > > > >
> > > > > My test consist in compiling gcc 3.0 while
> some MP3s are continously playing
> > > > > in the background. The gcc build goes
> pretty far along until both the mp3
> > > > > player and the gcc build completely jam.
> > > >
> > > > Which sound system, and which sound card
> driver?
> > >
> > > The driver is for the UDA1341 on a SA1110 chip
> written by myself. It is
> > > fully OSS compliant, no ALSA.
> >
> > Your system should be able to handle that easily.
> Do you have some meminfo
> > output to look at? What about 2.4.9?
>
> OK now I have some comparative data. Two kernels:
>
> 1) based on 2.4.8-ac9 + Riel's VM fixes from -ac10
> 2) based on 2.4.9 with no extra VM patches
>
>
> The test:
> =========
>
> 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.

Strange enough to me, I can not reproduce this with my
computer nearly the same as your described situation

Except nfs root file system, I started several rxvt
play mpg123 ; compile the kernel ; browsing the net
using mozilla, running top at one rxvt, kernel uses
2.4.9 is fine; 2.4.6 is fine too.

My computer is 686 128Mb RAM only 72Mb swap

OOP, 2.4.9 applied the one small patch for VM fix
(just one line
>
> 2.4.8-ac9 plus -ac10 VM fixes:
> ==============================
>
> Everything looks fine for a while. But all of a
> sudden: no more music, the
> gcc build stalls, system looks dead. In my first
> description of the problem
> quoted above I said that the audio was spitting
> glitches of 100 ms every 10
> secs or so. This time there is nothing. The only
> difference is the
> addition of 'top' in the process list. Even the
> telnet sessions aren't
> echoing keystrokes anymore. Only the serial console
> echoes characters so
> kernel BH's are still running. Sysrq on the serial
> console works
> fortunately. kswapd is looping like crazy:
>
> kswapd R C0023CC0 0 4 0
> 5 3 (L-TLB)
>
> At first NFS traffic occupied the full network
> bandwidth to page stuff in.
> But after a while the following was printed to the
> console:
>
> 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
>
> and then no more NFS packet on the network. It is
> possible to ping the box
> which means that the net BH still works.
>
> A couple sysrq-P at random intervals shows the CPU
> looping in the following
> functions:
>
> PC value System.map
> -------- ----------
> c0040d84 zone_inactive_plenty
> c0041024 try_to_swap_out
> c00216e0 cpu_sa1100_cache_clean_invalidate_range
> c00216d0 cpu_sa1100_cache_clean_invalidate_range
> c0041304 swap_out_mm
> c0041168 swap_out_pmd
> c0044324 __get_swap_page
> c0040d60 zone_inactive_plenty
> c0041128 swap_out_pmd
> c0040fec try_to_swap_out
>
> Sysrq-M gives:
>
> SysRq : Show Memory
> Mem-info:
> Free pages: 1012kB ( 0kB HighMem)
> ( Active: 2007, inactive_dirty: 0, inactive_clean:
> 0, free: 253 (255 510 765) )
> 3*4kB 1*8kB 0*16kB 1*32kB 1*64kB 1*128kB 1*256kB
> 1*512kB 0*1024kB 0*2048kB = 1012kB)
> = 0kB)
> = 0kB)
> Swap cache: add 0, delete 0, find 0/0
> Free swap: 0kB
> 8192 pages of RAM
> 393 free pages
> 636 reserved pages
> 33 pages shared
> 0 pages swap cached
> 6 page tables cached
> Buffer memory: 8000kB
>
>
> 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. kswapd is well
> locked in the R state:
>
> kswapd R C0022CA0 0 4 0
> 5 3 (L-TLB)
>
> 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.
>
> A couple sysrq-P at random intervals shows the CPU
> looping in the following
> functions:
>
> 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
>
> Sysrq-M gives:
>
> SysRq: Show Memory
> Mem-info:
> Free pages: 1008kB ( 0kB HighMem)
> ( Active: 2546, inactive_dirty: 63, inactive_clean:
> 0, free: 252 (255 510 765) )
> 0*4kB 0*8kB 1*16kB 1*32kB 1*64kB 1*128kB 1*256kB
> 1*512kB 0*1024kB 0*2048kB = 1008kB)
> = 0kB)
> = 0kB)
> Swap cache: add 0, delete 0, find 0/0
> Free swap: 0kB
> 8192 pages of RAM
> 392 free pages
> 602 reserved pages
> 576 pages shared
> 0 pages swap cached
> 8 page tables cached
> Buffer memory: 8000kB
>
>
> Notes:
> ======
>
> - Both kernels go flat after approx 14 min of mp3
> playback.
> - With enough retries (i.e. reboots) the gcc build
> succeed, so there is no
> lack of ressources in theory.
> - SEnding a signal to the mp3 player (^C on the
> serial
=== message truncated ===

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