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From: Ingo Molnar <mingo@elte.hu>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: penberg@kernel.org, avi@redhat.com, kvm@vger.kernel.org,
	asias.hejun@gmail.com, gorcunov@gmail.com,
	prasadjoshi124@gmail.com
Subject: Re: [PATCH 3/4] kvm tools: Add a brlock
Date: Sun, 29 May 2011 20:47:31 +0200	[thread overview]
Message-ID: <20110529184731.GB9835@elte.hu> (raw)
In-Reply-To: <1306690348-23260-3-git-send-email-levinsasha928@gmail.com>


* Sasha Levin <levinsasha928@gmail.com> wrote:

> +++ b/tools/kvm/include/kvm/brlock.h
> @@ -0,0 +1,12 @@
> +#ifndef KVM__BRLOCK_H
> +#define KVM__BRLOCK_H
> +
> +#include "kvm/kvm.h"
> +#include "kvm/barrier.h"
> +
> +#define br_read_lock()		mb()
> +#define br_read_unlock()	mb()

These only need to be compiler barrier()s AFAICS, because the 'pause' 
op will signal back to the requestor thread - which whole operation 
is a barrier to begin with.

> +#define br_write_lock()		kvm__pause()
> +#define br_write_unlock()	kvm__continue()
> +#endif

Btw., it might make sense to add a comment to this header file, 
explaining what a 'big reader lock' is :-)

Thanks,

	Ingo

  reply	other threads:[~2011-05-29 18:47 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-29 17:32 [PATCH 1/4] kvm tools: Use correct value for user signal base Sasha Levin
2011-05-29 17:32 ` [PATCH 2/4] kvm tools: Allow pausing guests Sasha Levin
2011-05-29 17:56   ` Sasha Levin
2011-05-29 17:32 ` [PATCH 3/4] kvm tools: Add a brlock Sasha Levin
2011-05-29 18:47   ` Ingo Molnar [this message]
2011-05-29 19:30     ` Sasha Levin
2011-05-29 19:38       ` Ingo Molnar
2011-05-29 17:32 ` [PATCH 4/4] kvm tools: Use brlock in MMIO and IOPORT Sasha Levin

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