From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?ISO-8859-1?Q?Roger_Pau_Monn=E9?= <roger.pau@citrix.com>
Subject: Re: [PATCH net-next v3 1/9] xen-netback: Introduce TX grant map definitions
Date: Thu, 9 Jan 2014 16:49:44 +0100
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References: <1389139818-24458-1-git-send-email-zoltan.kiss@citrix.com> <1389139818-24458-2-git-send-email-zoltan.kiss@citrix.com> <20140109153010.GE12164@zion.uk.xensource.com>
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To: Wei Liu <wei.liu2@citrix.com>, Zoltan Kiss <zoltan.kiss@citrix.com>
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On 09/01/14 16:30, Wei Liu wrote:
> On Wed, Jan 08, 2014 at 12:10:10AM +0000, Zoltan Kiss wrote:
>> This patch contains the new definitions necessary for grant mapping.
>>
>> v2:
>> - move unmapping to separate thread. The NAPI instance has to be scheduled
>>   even from thread context, which can cause huge delays
>> - that causes unfortunately bigger struct xenvif
>> - store grant handle after checking validity
>>
>> v3:
>> - fix comment in xenvif_tx_dealloc_action()
>> - call unmap hypercall directly instead of gnttab_unmap_refs(), which does
>>   unnecessary m2p_override. Also remove pages_to_[un]map members
> 
> Is it worthy to have another function call
> gnttab_unmap_refs_no_m2p_override in Xen core driver, or just add a
> parameter to control wether we need to touch m2p_override? I *think* it
> will benefit block driver as well?

Anthony Liguori posted a patch to perform something similar in blkback,
but I think the patch never made it upstream:

https://lkml.org/lkml/2013/11/12/749

Probably a good time to revisit it so this mechanism can be used by both
blkback and netback?

Roger.