From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org
Subject: Re: [patch] sched: fix scheduling latencies for !PREEMPT kernels
Date: Tue, 14 Sep 2004 23:33:48 +1000 [thread overview]
Message-ID: <4146F33C.9030504@yahoo.com.au> (raw)
In-Reply-To: <20040914132225.GA9310@elte.hu>
Ingo Molnar wrote:
> * Nick Piggin <nickpiggin@yahoo.com.au> wrote:
>
>
>>Could these ones go up a level? We break down scanning into 32 page
>>chunks, so I don't think it needs to be checked every page.
>
>
> not really - we can occasionally get into high latencies even with a
> single page - if a single page is mapped by alot of processes.
>
So doing it in the loop doesn't really give you a deterministic
maximum latency if somebody is out to cause trouble, does it?
OTOH, I guess libc or some shared memory segment may be mapped
into a lot of processes even on RT applictions.
Another thing, I don't mean this to sound like a rhetorical question,
but if we have a preemptible kernel, why is it a good idea to sprinkle
cond_rescheds everywhere? Isn't this now the worst of both worlds?
Why would someone who really cares about latency not enable preempt?
next prev parent reply other threads:[~2004-09-14 13:37 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-14 9:15 [patch] preempt-cleanup.patch, 2.6.9-rc2 Ingo Molnar
2004-09-14 9:34 ` [printk] make console_conditional_schedule() __sched and use cond_resched() William Lee Irwin III
2004-09-14 9:38 ` [patch] preempt-lock-need-resched.patch, 2.6.9-rc2 Ingo Molnar
2004-09-14 9:51 ` [patch] sched: add cond_resched_softirq() Ingo Molnar
2004-09-14 9:57 ` [patch] sched: fix latency in random driver Ingo Molnar
2004-09-14 10:06 ` [patch] sched, ext3: fix scheduling latencies in ext3 Ingo Molnar
2004-09-14 10:13 ` [patch] sched, vfs: fix scheduling latencies in invalidate_inodes() Ingo Molnar
2004-09-14 10:19 ` [patch] sched, vfs: fix scheduling latencies in prune_dcache() and select_parent() Ingo Molnar
2004-09-14 10:25 ` [patch] sched, net: fix scheduling latencies in netstat Ingo Molnar
2004-09-14 10:44 ` [patch] sched, net: fix scheduling latencies in __release_sock Ingo Molnar
2004-09-14 10:50 ` [patch] sched, mm: fix scheduling latencies in copy_page_range() Ingo Molnar
2004-09-14 10:56 ` [patch] sched, mm: fix scheduling latencies in unmap_vmas() Ingo Molnar
2004-09-14 10:59 ` [patch] sched, mm: fix scheduling latencies in get_user_pages() Ingo Molnar
2004-09-14 11:02 ` [patch] sched, mm: fix scheduling latencies in filemap_sync() Ingo Molnar
2004-09-14 11:06 ` [patch] sched, tty: fix scheduling latencies in tty_io.c Ingo Molnar
2004-09-14 10:53 ` Alan Cox
2004-09-14 12:00 ` Ingo Molnar
2004-09-14 11:18 ` Alan Cox
2004-09-14 12:27 ` Ingo Molnar
2004-09-14 12:11 ` Alan Cox
2004-09-14 11:08 ` [patch] sched, pty: fix scheduling latencies in pty.c Ingo Molnar
2004-09-14 11:12 ` [patch] might_sleep() additions to fs-writeback.c Ingo Molnar
2004-09-14 11:25 ` [patch] fix keventd execution dependency Ingo Molnar
2004-09-15 22:18 ` Rusty Russell
2004-09-14 11:28 ` [patch] sched: fix scheduling latencies in mttr.c Ingo Molnar
2004-09-14 11:32 ` [patch] sched: fix scheduling latencies in vgacon.c Ingo Molnar
2004-09-14 11:35 ` [patch] sched: fix scheduling latencies in NTFS mount Ingo Molnar
2004-09-14 13:31 ` Anton Altaparmakov
2004-09-14 11:42 ` [patch] sched: fix scheduling latencies for !PREEMPT kernels Ingo Molnar
2004-09-14 12:55 ` Nick Piggin
2004-09-14 13:22 ` Ingo Molnar
2004-09-14 13:33 ` Nick Piggin [this message]
2004-09-14 14:09 ` Andrea Arcangeli
2004-09-14 14:28 ` Nick Piggin
2004-09-14 15:03 ` Andrea Arcangeli
2004-09-14 18:05 ` Robert Love
2004-09-14 18:52 ` William Lee Irwin III
2004-09-14 19:02 ` Robert Love
2004-09-14 19:21 ` William Lee Irwin III
2004-09-14 19:19 ` Alan Cox
2004-09-15 0:22 ` Lee Revell
2004-09-15 1:46 ` William Lee Irwin III
2004-09-15 2:00 ` Lee Revell
2004-09-15 2:36 ` William Lee Irwin III
2004-09-15 2:59 ` Lee Revell
2004-09-15 13:36 ` Hans Reiser
2004-09-15 20:40 ` William Lee Irwin III
2004-09-15 1:18 ` William Lee Irwin III
2004-09-14 19:26 ` Robert Love
2004-09-14 21:06 ` William Lee Irwin III
2004-09-14 19:25 ` Andrea Arcangeli
2004-09-14 19:29 ` Robert Love
2004-09-14 19:34 ` William Lee Irwin III
2004-09-15 1:02 ` Lee Revell
2004-09-15 1:39 ` William Lee Irwin III
2004-09-15 2:11 ` Lee Revell
2004-09-15 11:17 ` Ingo Molnar
2004-09-15 9:56 ` Ingo Molnar
2004-09-15 9:57 ` William Lee Irwin III
2004-09-15 10:12 ` Ingo Molnar
2004-09-14 16:31 ` William Lee Irwin III
2004-09-14 16:39 ` Andrea Arcangeli
2004-09-14 14:54 ` Ingo Molnar
2004-09-14 22:55 ` Nick Piggin
2004-09-15 6:19 ` Ingo Molnar
2004-09-15 8:23 ` Nick Piggin
2004-09-15 8:43 ` Ingo Molnar
2004-09-15 10:09 ` William Lee Irwin III
2004-09-15 10:21 ` Ingo Molnar
2004-09-16 1:03 ` Nick Piggin
2004-09-16 6:14 ` Ingo Molnar
2004-09-15 0:35 ` Lee Revell
2004-09-14 13:25 ` [patch] sched: fix scheduling latencies in mtrr.c Ingo Molnar
2004-09-14 13:15 ` Alan Cox
2004-09-14 15:00 ` Ingo Molnar
2004-09-14 18:22 ` Zwane Mwaikambo
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