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From: Andi Kleen <ak@suse.de>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: virtualization@lists.osdl.org, john stultz <johnstul@us.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [patch 17/17] Add a sched_clock paravirt_op
Date: Mon, 2 Apr 2007 08:50:32 +0200	[thread overview]
Message-ID: <200704020850.32274.ak@suse.de> (raw)
In-Reply-To: <4610A70A.7010105@goop.org>

On Monday 02 April 2007 08:47, Jeremy Fitzhardinge wrote:
> Andi Kleen wrote:
> > I think it would be much cleaner if you didn't implement your own sched_clock,
> > but you adjust ns_base/last_tsc to account for your lost cycles.
> > This could be done cleanly by adding a new function to sched-clock.c
> > Possibly such a function could be used by other parts of the kernel
> > in the future too.
> >   
> 
> Cleaner how?  This seems pretty to me.  Xen can return a
> clock measuring unstolen nanoseconds, 

Do you also get a clock for stolen nanoseconds? 

> which maps directly to the 
> sched_clock interface, doesn't need any of the existing sched_clock
> code.  I suppose I could map the Xen interface onto some abstract
> "cycles" notion and hook it into the tsc machinery, but it seems like it
> would be a forced fit.  In general, my approach has been to choose the
> higher-level interface over a lower-level one, all other things being equal.

No need for cycles, you could just subtract the stolen ns if you
can get those.

-Andi

  reply	other threads:[~2007-04-02  6:50 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-02  5:56 [patch 00/17] paravirt_ops updates Jeremy Fitzhardinge
2007-04-02  5:56 ` [patch 01/17] update MAINTAINERS Jeremy Fitzhardinge
2007-04-02  5:56 ` [patch 02/17] Remove CONFIG_DEBUG_PARAVIRT Jeremy Fitzhardinge
2007-04-02  5:56 ` [patch 03/17] use paravirt_nop to consistently mark no-op operations Jeremy Fitzhardinge
2007-04-02  5:56 ` [patch 04/17] Add pagetable accessors to pack and unpack pagetable entries Jeremy Fitzhardinge
2007-04-02  6:12   ` Andi Kleen
2007-04-02  6:35     ` Rusty Russell
2007-04-02  6:48     ` Jeremy Fitzhardinge
2007-04-04  9:25     ` Jeremy Fitzhardinge
2007-04-04 11:47       ` Andi Kleen
2007-04-04 15:45         ` Jeremy Fitzhardinge
2007-04-04 15:56           ` Andi Kleen
2007-04-04 16:04             ` Jeremy Fitzhardinge
2007-04-04 22:59             ` Rusty Russell
2007-04-04 23:39               ` Jeremy Fitzhardinge
2007-04-02  5:56 ` [patch 05/17] Hooks to set up initial pagetable Jeremy Fitzhardinge
2007-04-02  5:56 ` [patch 06/17] Allocate a fixmap slot Jeremy Fitzhardinge
2007-04-02  5:56 ` [patch 07/17] Allow paravirt backend to choose kernel PMD sharing Jeremy Fitzhardinge
2007-04-02  5:57 ` [patch 08/17] add hooks to intercept mm creation and destruction Jeremy Fitzhardinge
2007-04-02  5:57 ` [patch 09/17] rename struct paravirt_patch to paravirt_patch_site for clarity Jeremy Fitzhardinge
2007-04-02  5:57 ` [patch 10/17] Use patch site IDs computed from offset in paravirt_ops structure Jeremy Fitzhardinge
2007-04-02  5:57 ` [patch 11/17] Fix patch site clobbers to include return register Jeremy Fitzhardinge
2007-04-02  5:57 ` [patch 12/17] Consistently wrap paravirt ops callsites to make them patchable Jeremy Fitzhardinge
2007-04-02  7:11   ` Andi Kleen
2007-04-02  7:20     ` Jeremy Fitzhardinge
2007-04-02  5:57 ` [patch 13/17] add common patching machinery Jeremy Fitzhardinge
2007-04-02  5:57 ` [patch 14/17] add flush_tlb_others paravirt_op Jeremy Fitzhardinge
2007-04-02  5:57 ` [patch 15/17] revert map_pt_hook Jeremy Fitzhardinge
2007-04-02  5:57 ` [patch 16/17] add kmap_atomic_pte for mapping highpte pages Jeremy Fitzhardinge
2007-04-02  7:18   ` Andi Kleen
2007-04-02  7:22     ` Jeremy Fitzhardinge
2007-04-02  5:57 ` [patch 17/17] Add a sched_clock paravirt_op Jeremy Fitzhardinge
2007-04-02  6:09   ` Andi Kleen
2007-04-02  6:47     ` Jeremy Fitzhardinge
2007-04-02  6:50       ` Andi Kleen [this message]
2007-04-02  7:06         ` Jeremy Fitzhardinge

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