 Home |
Products |
Support |
Community |
News |
xen-devel
Re: [Xen-devel] [PATCH 12/17] xenpaging: handle HVMCOPY_gfn_paged_out in
| To: | Olaf Hering <olaf@xxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] [PATCH 12/17] xenpaging: handle HVMCOPY_gfn_paged_out in copy_from/to_user |
| From: | Keir Fraser <keir@xxxxxxx> |
| Date: | Wed, 15 Dec 2010 11:35:21 +0000 |
| Cc: | |
| Delivery-date: | Wed, 15 Dec 2010 03:36:39 -0800 |
| Dkim-signature: | v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:sender:user-agent:date :subject:from:to:message-id:thread-topic:thread-index:in-reply-to :mime-version:content-type:content-transfer-encoding; bh=q+L/KcU9rxbgcgUPr63liy4GbbdsZCsDMxkolXuhoXQ=; b=a6Um34KA49AshOSAFA0JXnD/ew5DYB+a6PiEiq71qRrn867MY6Id5me8RLV1Znpwgl WJ/awbHx04Xz/F0hKEzLj3bh9Y98IMPFougZtqNyLQ1iRzfSKoIckOQoPyQB/w69Xcvw Vw3/775YEyQC3Yw7YRRtp1kgTK4UOifzKhMbk= |
| Domainkey-signature: | a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:user-agent:date:subject:from:to:message-id:thread-topic :thread-index:in-reply-to:mime-version:content-type :content-transfer-encoding; b=llE5dsqPUkT9JscvpFs/eeXQCJJVLL0UJZrMURFBKo0IaFgVC0MLZXLwTj2lK5uuqO LWGgNUMyYiGCUVAesCLV5yHVqNXFuGJbJDLC0ZiAUV3zmzfgT5c2c7kz8McyYuLhc8g/ ZTV+dei6rbKOrkv/ecP4MpouztfNfgjYiTUH4= |
| Envelope-to: | www-data@xxxxxxxxxxxxxxxxxxx |
| In-reply-to: | <20101206205912.343173055@xxxxxxxxx> |
| List-help: | <mailto:xen-devel-request@lists.xensource.com?subject=help> |
| List-id: | Xen developer discussion <xen-devel.lists.xensource.com> |
| List-post: | <mailto:xen-devel@lists.xensource.com> |
| List-subscribe: | <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe> |
| List-unsubscribe: | <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe> |
| Sender: | xen-devel-bounces@xxxxxxxxxxxxxxxxxxx |
| Thread-index: | AcucTCfWAAEv1CpmsE2PNtP64KxlTw== |
| Thread-topic: | [Xen-devel] [PATCH 12/17] xenpaging: handle HVMCOPY_gfn_paged_out in copy_from/to_user |
| User-agent: | Microsoft-Entourage/12.27.0.100910 |
On 06/12/2010 20:59, "Olaf Hering" <olaf@xxxxxxxxx> wrote:
> mem_event_put_request(d, &req);
> +
> + if ( req.flags & MEM_EVENT_FLAG_VCPU_PAUSED )
> + {
> + wait_event(d->wq, mfn_valid(gfn_to_mfn(p2m, gfn, &p2mt)) &&
> !p2m_is_paging(p2mt));
> + }
> +
This I find interesting. Do you not race the xenpaging daemon satisfying
your page-in request, but then very quickly paging it out again? In which
case you might never wake up!
I think the condition you wait on should be for a response to your paging
request. A wake_up() alone is not really sufficient; you need some kind of
explicit flagging to the vcpu too. Could the paging daemon stick a response
in a shared ring, or otherwise explicitly flag to this vcpu that it's
request has been fully satisfied and it's time to wake up and retry its
operation? Well, really that's a rhetorical question, because that is
exactly what you need to implement for this waitqueue strategy to work
properly!
-- Keir
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
| Previous by Date: | Re: [Xen-devel] [PATCH] svm: support VMCB cleanbits, Tim Deegan |
|---|---|
| Next by Date: | [Xen-devel] [PATCH][TOOLS] libxc: finish discard_file_cache() for NetBSD, Christoph Egger |
| Previous by Thread: | Re: [Xen-devel] [PATCH 12/17] xenpaging: handle HVMCOPY_gfn_paged_out in copy_from/to_user, Olaf Hering |
| Next by Thread: | Re: [Xen-devel] [PATCH 12/17] xenpaging: handle HVMCOPY_gfn_paged_out in copy_from/to_user, Olaf Hering |
| Indexes: | [Date] [Thread] [Top] [All Lists] |
