linux-kernel - Re: [RFC PATCH 0/6] Convert all tasklets to workqueues

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Date:	Mon, 25 Jun 2007 22:01:16 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Dan Williams <dan.j.williams@...el.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Christoph Hellwig <hch@...radead.org>,
	john stultz <johnstul@...ibm.com>,
	Oleg Nesterov <oleg@...sign.ru>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Dipankar Sarma <dipankar@...ibm.com>,
	"David S. Miller" <davem@...emloft.net>, kuznet@....inr.ac.ru
Subject: Re: [RFC PATCH 0/6] Convert all tasklets to workqueues

On Mon, 2007-06-25 at 18:46 -0700, Dan Williams wrote:
> 
> Context switches on this platform flush the L1 cache so bouncing
> between a workqueue and the MD thread is painful.

Why is context switches between two kernel threads flushing the L1
cache?  Is this a flaw in the ARM arch?  I would think the only thing
that needs to be done between a context switch of two kernel threads (or
even a user thread to a kernel thread) is update the general regs and
stack. The memory access (page_tables or whatever ARM uses) should stay
the same.

Perhaps something else is at fault here.

Thanks for testing!

-- Steve


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