From: Peter Zijlstra <peterz@infradead.org>
To: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com,
paulus@samba.org, acme@redhat.com, efault@gmx.de,
npiggin@suse.de, tglx@linutronix.de,
linux-tip-commits@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>
Subject: Re: [tip:perfcounters/core] x86: Add NMI types for kmap_atomic
Date: Wed, 17 Jun 2009 09:58:38 +0200 [thread overview]
Message-ID: <1245225518.13761.21617.camel@twins> (raw)
In-Reply-To: <Pine.LNX.4.64.0906161312440.552@sister.anvils>
On Tue, 2009-06-16 at 13:38 +0100, Hugh Dickins wrote:
>
> Something else to throw in: what if they were not just atomic,
> but also replaced the current sleeping kmaps? i.e. a task context
> carries around its own stack of these.
I actually did that once, but it means the task needs to be cpu-affine,
because fixmaps have different addresses between cpus. And disabling
migration for tasks has subtle side-effects so I dropped that again.
However, I recently considered the possiblity of putting the fixmaps in
the new per-cpu address space so that we might use the %gs segment to
normalize the fixmap addresses between the cpus.
This would allow full preemptible kmaps (yay for -rt).
However I suspect it might greatly complicate kmaps for the !i386 world.
next prev parent reply other threads:[~2009-06-17 7:59 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <tip-3ff0141aa3a03ca3388b40b36167d0a37919f3fd@git.kernel.org>
2009-06-15 14:46 ` [tip:perfcounters/core] x86: Add NMI types for kmap_atomic Peter Zijlstra
2009-06-15 15:30 ` Hugh Dickins
2009-06-15 15:41 ` Peter Zijlstra
2009-06-15 15:52 ` Ingo Molnar
2009-06-15 16:02 ` Hugh Dickins
2009-06-15 18:04 ` Peter Zijlstra
2009-06-15 18:15 ` Ingo Molnar
2009-06-15 18:19 ` Peter Zijlstra
2009-06-15 18:25 ` Ingo Molnar
2009-06-15 18:30 ` Peter Zijlstra
2009-06-15 18:42 ` Ingo Molnar
2009-06-15 18:47 ` Peter Zijlstra
2009-06-15 18:52 ` Ingo Molnar
2009-06-15 19:00 ` Peter Zijlstra
2009-06-16 8:13 ` Ingo Molnar
2009-06-16 12:38 ` Hugh Dickins
2009-06-17 7:58 ` Peter Zijlstra [this message]
2009-06-17 8:43 ` Tejun Heo
2009-06-17 9:05 ` Peter Zijlstra
2009-06-17 7:44 ` Peter Zijlstra
2009-06-17 12:28 ` Ingo Molnar
2009-06-15 18:42 ` Andrew Morton
2009-06-15 18:45 ` Peter Zijlstra
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