From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff Garzik <jeff@garzik.org>
Subject: Re: [take21 0/4] kevent: Generic event handling mechanism.
Date: Tue, 07 Nov 2006 07:32:20 -0500
Message-ID: <45507CD4.5030600@garzik.org>
References: <11619654014077@2ka.mipt.ru> <45506D51.30604@garzik.org> <20061107115111.GA13028@2ka.mipt.ru>
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Cc: David Miller <davem@davemloft.net>,
	Ulrich Drepper <drepper@redhat.com>,
	Andrew Morton <akpm@osdl.org>, netdev <netdev@vger.kernel.org>,
	linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@osdl.org>
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To: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
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Evgeniy Polyakov wrote:
> Mmap ring buffer implementation was stopped by Andrew Morton and Ulrich
> Drepper, process' memory is used instead. copy_to_user() is slower (and
> some times noticebly), but there are major advantages of such approach.


hmmmm.  I say there are advantages to both.

Perhaps create a "kevent_direct_limit" resource limit for each thread. 
By default, each thread could mmap $n pinned pagecache pages.  Sysadmin 
can tune certain app resource limits to permit more.

I would think that retaining the option to avoid copy_to_user() 
-somehow- in -some- cases would be wise.

	Jeff