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From: Avi Kivity <avi@redhat.com>
To: Gregory Haskins <ghaskins@novell.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	linux-kernel@vger.kernel.org, agraf@suse.de,
	pmullaney@novell.com, pmorreale@novell.com,
	anthony@codemonkey.ws, rusty@rustcorp.com.au,
	netdev@vger.kernel.org, kvm@vger.kernel.org,
	bhutchings@solarflare.com, andi@firstfloor.org, gregkh@suse.de,
	herber@gondor.apana.org.au, chrisw@sous-sol.org,
	shemminger@vyatta.com
Subject: Re: [RFC PATCH v2 03/19] vbus: add connection-client helper infrastructure
Date: Thu, 04 Jun 2009 22:04:09 +0300	[thread overview]
Message-ID: <4A281AA9.50209@redhat.com> (raw)
In-Reply-To: <4A2812E3.6090108@novell.com>

Gregory Haskins wrote:
> Oh, I don't doubt that (in fact, I was pretty sure that was the case
> based on some of the optimizations I could see in studying the c_t_u()
> path).  I just didn't realize there were other ways to do it if its a
> non "current" task. ;)
>
> I guess the enigma for me right now is what cost does switch_mm have? 
> (Thats not a slam against the suggested approach...I really do not know
> and am curious).
>   

switch_mm() is probably very cheap (reloads cr3), but it does dirty the 
current cpu's tlb.  When the kernel needs to flush a process' tlb, it 
will have to IPI that cpu in addition to all others.  This takes place, 
for example, after munmap() or after a page is swapped out (though 
significant batching is done there).

It's still plenty cheaper in my estimation.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.


  reply	other threads:[~2009-06-04 19:05 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-09 16:30 [RFC PATCH v2 00/19] virtual-bus Gregory Haskins
2009-04-09 16:30 ` [RFC PATCH v2 01/19] shm-signal: shared-memory signals Gregory Haskins
2009-04-09 16:30 ` [RFC PATCH v2 02/19] vbus: add virtual-bus definitions Gregory Haskins
2009-04-09 16:30 ` [RFC PATCH v2 03/19] vbus: add connection-client helper infrastructure Gregory Haskins
2009-06-04 18:06   ` Michael S. Tsirkin
2009-06-04 18:18     ` Gregory Haskins
2009-06-04 18:24       ` Avi Kivity
2009-06-04 18:30         ` Gregory Haskins
2009-06-04 19:04           ` Avi Kivity [this message]
2009-06-04 18:23     ` Avi Kivity
2009-04-09 16:31 ` [RFC PATCH v2 04/19] vbus: add bus-registration notifiers Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 05/19] vbus: add a "vbus-proxy" bus model for vbus_driver objects Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 06/19] ioq: Add basic definitions for a shared-memory, lockless queue Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 07/19] ioq: add vbus helpers Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 08/19] venet: add the ABI definitions for an 802.x packet interface Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 09/19] net: Add vbus_enet driver Gregory Haskins
2009-04-09 16:37   ` Stephen Hemminger
2009-04-09 19:50     ` Greg KH
2009-04-09 16:31 ` [RFC PATCH v2 10/19] venet-tap: Adds a "venet" compatible "tap" device to VBUS Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 11/19] venet: add scatter-gather support Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 12/19] venettap: " Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 13/19] x86: allow the irq->vector translation to be determined outside of ioapic Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 14/19] kvm: add a reset capability Gregory Haskins
2009-04-11 16:56   ` Avi Kivity
2009-04-09 16:32 ` [RFC PATCH v2 15/19] kvm: add dynamic IRQ support Gregory Haskins
2009-04-11 17:01   ` Avi Kivity
2009-04-13 17:44     ` Gregory Haskins
2009-04-09 16:32 ` [RFC PATCH v2 16/19] kvm: Add VBUS support to the host Gregory Haskins
2009-04-09 16:32 ` [RFC PATCH v2 17/19] kvm: Add guest-side support for VBUS Gregory Haskins
2009-04-09 16:32 ` [RFC PATCH v2 18/19] vbus: add a userspace connector Gregory Haskins
2009-04-09 16:32 ` [RFC PATCH v2 19/19] virtio: add a vbus transport Gregory Haskins
2009-08-09 16:40   ` Anthony Liguori
2009-08-10 15:40     ` Gregory Haskins
2009-04-09 16:48 ` [RFC PATCH v2 00/19] virtual-bus Gregory Haskins
2009-04-11 16:45   ` Avi Kivity
2009-06-04 18:49     ` Gregory Haskins
2009-06-05  4:55       ` Rusty Russell
2009-06-05  5:30         ` Paul E. McKenney
2009-06-05 14:55           ` Rusty Russell
2009-06-05 16:25             ` Paul E. McKenney
2009-06-05 11:56         ` Gregory Haskins
2009-06-05 12:53           ` Avi Kivity
2009-06-05 12:54             ` Gregory Haskins
2009-06-05 14:35           ` Rusty Russell
2009-06-05 14:44             ` Gregory Haskins

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