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SubjectRe: [patch] voluntary-preempt-2.6.9-rc1-bk12-R6
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On Fri, 2004-09-10 at 09:28, Ingo Molnar wrote:
> * Andrew Morton <akpm@osdl.org> wrote:
>
> > diff -puN mm/vmscan.c~swapspace-layout-improvements mm/vmscan.c
> > --- 25/mm/vmscan.c~swapspace-layout-improvements 2004-06-03 21:32:51.087602712 -0700
> > +++ 25-akpm/mm/vmscan.c 2004-06-03 21:32:51.102600432 -0700
>

OK, Andrew's patch seems to be an improvement. I can still cause
unbounded latencies, but these only seem to happen when we fill all
available RAM and swap space, at which point we start spending
milliseconds at a time in scan_swap_map:


preemption latency trace v1.0.7 on 2.6.9-rc1-bk12-VP-S0
-------------------------------------------------------
latency: 6032 us, entries: 550 (550) | [VP:1 KP:1 SP:1 HP:1 #CPUS:1]
-----------------
| task: xfs/1098, uid:0 nice:0 policy:0 rt_prio:0
-----------------
=> started at: rtc_interrupt+0x294/0x450
=> ended at: get_swap_page+0x13f/0x350
=======>
00010002 0.000ms (+0.000ms): touch_preempt_timing (rtc_interrupt)
00010002 0.000ms (+0.000ms): printk (rtc_interrupt)
00010002 0.000ms (+0.001ms): vprintk (printk)
00010003 0.002ms (+0.000ms): vscnprintf (vprintk)
00010003 0.002ms (+0.002ms): vsnprintf (vscnprintf)
00010003 0.005ms (+0.004ms): number (vsnprintf)
00010003 0.009ms (+0.001ms): number (vsnprintf)
00010003 0.010ms (+0.001ms): number (vsnprintf)
00010003 0.011ms (+0.000ms): emit_log_char (vprintk)

[...]

00010002 1.983ms (+0.000ms): preempt_schedule (do_IRQ)
00000003 1.984ms (+0.000ms): do_softirq (do_IRQ)
00000003 1.984ms (+0.911ms): __do_softirq (do_softirq)
00010002 2.896ms (+0.000ms): do_IRQ (scan_swap_map)
00010002 2.896ms (+0.000ms): do_IRQ (<00000008>)
00010003 2.897ms (+0.004ms): mask_and_ack_8259A (do_IRQ)
00010003 2.901ms (+0.000ms): preempt_schedule (do_IRQ)

Full trace:

http://krustophenia.net/testresults.php?dataset=2.6.9-rc1-bk12-S0#/var/www/2.6.9-rc1-bk12-S0/swapspace-layout-improvements-A1.txt

The above are just the initial results; I am still testing this. It
certainly seems like it can take a beating.

Lee

Lee

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