On 11/2/07, Fengguang Wu <wfg@mail.ustc.edu.cn> wrote:
quoted text > On Thu, Nov 01, 2007 at 08:00:10PM +0100, Torsten Kaiser wrote:
> > On 11/1/07, Torsten Kaiser <just.for.lkml@googlemail.com> wrote:
> > > On 11/1/07, Fengguang Wu <wfg@mail.ustc.edu.cn> wrote:
> > > > Thank you. Maybe we can start by the applied debug patch :-)
> > >
> > > Will applied it and try to recreate this.
> >
> > Patch applied, used emerge to install a 2.6.24-rc1 kernel.
> >
> > I had no complete stalls, but three times during the move from tmpfs
> > to the main xfs the emerge got noticeable slower. There still was
> > writeout happening, but as emerge prints out every file it has written
> > during the pause not one file was processed.
> >
> > vmstat 10:
> > procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
> > r b swpd free buff cache si so bi bo in cs us sy id wa
> > 0 1 0 3146424 332 614768 0 0 134 1849 438 2515 3 4 91 2
> > 0 0 0 3146644 332 614784 0 0 2 1628 507 646 0 2 85 13
> > 0 0 0 3146868 332 614868 0 0 5 2359 527 1076 0 3 97 0
> > 1 0 0 3144372 332 616148 0 0 96 2829 607 2666 2 5 92 0
> > -> normal writeout
> > 0 0 0 3140560 332 618144 0 0 152 2764 633 3308 3 6 91 0
> > 0 0 0 3137332 332 619908 0 0 114 1801 588 2858 3 4 93 0
> > 0 0 0 3136912 332 620136 0 0 20 827 393 1605 1 2 98 0
> > -> first stall
>
> 'stall': vmstat's output stalls for some time, or emerge stalls for
> the next several vmstat lines?
emerge stalls. The vmstat did work normally.
quoted text > > 0 0 0 3137088 332 620136 0 0 0 557 339 1437 0 1 99 0
> > 0 0 0 3137160 332 620136 0 0 0 642 310 1400 0 1 99 0
So meaning that these last three lines indicated that for ~30 seconds
the writeout was much slower than normal.
quoted text > > 0 0 0 3136588 332 620172 0 0 6 2972 527 1195 0 3 80 16
> > 0 0 0 3136276 332 620348 0 0 10 2668 558 1195 0 3 96 0
> > 0 0 0 3135228 332 620424 0 0 8 2712 522 1311 0 4 96 0
> > 0 0 0 3131740 332 621524 0 0 75 2935 559 2457 2 5 93 0
> > 0 0 0 3128348 332 622972 0 0 85 1470 490 2607 3 4 93 0
> > 0 0 0 3129292 332 622972 0 0 0 527 353 1398 0 1 99 0
> > -> second longer stall
> > 0 0 0 3128520 332 623028 0 0 6 488 249 1390 0 1 99 0
> > 0 0 0 3128236 332 623028 0 0 0 482 222 1222 0 1 99 0
> > 0 0 0 3128408 332 623028 0 0 0 585 269 1301 0 0 99 0
> > 0 0 0 3128532 332 623028 0 0 0 610 262 1278 0 0 99 0
> > 0 0 0 3128568 332 623028 0 0 0 636 345 1639 0 1 99 0
> > 0 0 0 3129032 332 623040 0 0 1 664 337 1466 0 1 99 0
> > 0 0 0 3129484 332 623040 0 0 0 658 300 1508 0 0 100 0
> > 0 0 0 3129576 332 623040 0 0 0 562 271 1454 0 1 99 0
> > 0 0 0 3129736 332 623040 0 0 0 627 278 1406 0 1 99 0
> > 0 0 0 3129368 332 623040 0 0 0 507 274 1301 0 1 99 0
> > 0 0 0 3129004 332 623040 0 0 0 444 211 1213 0 0 99 0
The second time the slowdown was much longer.
quoted text > > 0 1 0 3127260 332 623040 0 0 0 1036 305 1242 0 1 95 4
> > 0 0 0 3126280 332 623128 0 0 7 4241 555 1575 1 5 84 10
> > 0 0 0 3124948 332 623232 0 0 6 4194 529 1505 1 4 95 0
> > 0 0 0 3125228 332 624168 0 0 58 1966 586 1964 2 4 94 0
> > -> emerge resumed to normal speed, without any intervention from my side
> > 0 0 0 3120932 332 625904 0 0 112 1546 546 2565 3 4 93 0
> > 0 0 0 3118012 332 627568 0 0 128 1542 612 2705 3 4 93 0
>
> Interesting, the 'bo' never falls to zero.
Yes, I was not able to recreate the complete stall from the first
mail, but even this slowdown does not look completly healthy.
I "hope" this is the same bug, as I seem to be able to trigger this
slowdown much easier.
[snip logs]
quoted text >
> Interestingly, no background_writeout() appears, but only
> balance_dirty_pages() and wb_kupdate. Obviously wb_kupdate won't
> block the process.
Yes, I noticed that too.
The only time I have seen background_writeout was during bootup and shutdown.
As for the stalled watch cat /proc/meminfo:
That happend on the third slowdown/stall when emerge was already finished
quoted text > > If I see the complete stall again, I will post that too.
>
> Thank you, could you run it with the attached new debug patch?
I will, but it will have to wait until the evening.
Torsten
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