From: julien.grall@citrix•com (Julien Grall)
To: linux-arm-kernel@lists•infradead.org
Subject: [Xen-devel] [PATCH v2 15/20] block/xen-blkfront: Make it running on 64KB page granularity
Date: Tue, 21 Jul 2015 14:07:54 +0100 [thread overview]
Message-ID: <55AE442A.6080506@citrix.com> (raw)
In-Reply-To: <55AE27C2.8090803@citrix.com>
Hi Roger,
On 21/07/15 12:06, Roger Pau Monn? wrote:
> El 09/07/15 a les 22.42, Julien Grall ha escrit:
>> From: Julien Grall <julien.grall@linaro•org>
>>
>> The PV block protocol is using 4KB page granularity. The goal of this
>> patch is to allow a Linux using 64KB page granularity using block
>> device on a non-modified Xen.
>>
>> The block API is using segment which should at least be the size of a
> ^ segments
Will fix it.
>> Linux page. Therefore, the driver will have to break the page in chunk
> chunks ^
>> of 4K before giving the page to the backend.
>>
>> Breaking a 64KB segment in 4KB chunk will result to have some chunk with
>> no data.
>
> I would rewrite this as:
>
> Breaking a 64KB page into 4KB chunks can result in chunks with no data.
Sounds good.
>> As the PV protocol always require to have data in the chunk, we
>> have to count the number of Xen page which will be in use and avoid to
> ^ pages remove the "to" ^
>> sent empty chunk.
> ^ sending empty chunks
>>
>> Note that, a pre-defined number of grant is reserved before preparing
> ^ no coma ^ grants are
>> the request. This pre-defined number is based on the number and the
>> maximum size of the segments. If each segment contain a very small
> ^ contains
>> amount of data, the driver may reserve too much grant (16 grant is
> ^ many grants? ^ grants are
>> reserved per segment with 64KB page granularity).
>>
>> Futhermore, in the case of persistent grant we allocate one Linux page
> ^ Furthermore ^ case of using persistent grants
>> per grant although only the 4KB of the page will be effectively use.
> ^ initial ^ used.
>> This could be improved by share the page with multiple grants.
> ^ sharing the page between
Will fix all the typoes, grammatical error in the next version.
>>
>> Signed-off-by: Julien Grall <julien.grall@citrix•com>
>> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle•com>
>> Cc: Roger Pau Monn? <roger.pau@citrix•com>
>> Cc: Boris Ostrovsky <boris.ostrovsky@oracle•com>
>> Cc: David Vrabel <david.vrabel@citrix•com>
>
> This looks much better now, thanks.
>
> Acked-by: Roger Pau Monn? <roger.pau@citrix•com>
Thank you!
>> BUG_ON(info->max_indirect_segments == 0 &&
>> - req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
>> + (XEN_PAGES_PER_SEGMENT * req->nr_phys_segments) > BLKIF_MAX_SEGMENTS_PER_REQUEST);
>> BUG_ON(info->max_indirect_segments &&
>> - req->nr_phys_segments > info->max_indirect_segments);
>> + (req->nr_phys_segments * XEN_PAGES_PER_SEGMENT) > info->max_indirect_segments);
>> nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
>> + nr_page = 0;
>> + /* Calculate the number of Xen pages used */
>> + for_each_sg(info->shadow[id].sg, sg, nseg, i) {
>> + nr_page += (round_up(sg->offset + sg->length, XEN_PAGE_SIZE) - round_down(sg->offset, XEN_PAGE_SIZE)) >> XEN_PAGE_SHIFT;
>
> I haven't counted the characters, but this line looks too long, also you
> can get rid of the braces since it's a single line statement.
I was planning to use gnttab_count_grant added in patch #3 but forgot to
do it. I will do in the next version.
Regards,
--
Julien Grall
next prev parent reply other threads:[~2015-07-21 13:07 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-09 20:42 [PATCH v2 00/20] xen/arm64: Add support for 64KB page Julien Grall
2015-07-09 20:42 ` [PATCH v2 01/20] xen: Add Xen specific page definition Julien Grall
2015-07-16 14:19 ` Stefano Stabellini
2015-07-16 14:52 ` Julien Grall
2015-07-24 9:28 ` [Xen-devel] " David Vrabel
2015-07-24 9:39 ` Julien Grall
2015-07-24 9:48 ` David Vrabel
2015-07-24 9:51 ` Julien Grall
2015-07-24 10:34 ` David Vrabel
2015-07-24 10:43 ` Ian Campbell
2015-07-24 13:03 ` Julien Grall
2015-07-09 20:42 ` [PATCH v2 02/20] xen: Introduce a function to split a Linux page into Xen page Julien Grall
2015-07-16 14:23 ` Stefano Stabellini
2015-07-16 14:54 ` [Xen-devel] " Julien Grall
2015-07-24 9:31 ` David Vrabel
2015-07-24 9:54 ` Julien Grall
2015-07-24 10:10 ` David Vrabel
2015-07-24 10:20 ` Julien Grall
2015-08-05 14:30 ` Julien Grall
2015-08-05 15:50 ` David Vrabel
2015-08-05 16:06 ` Julien Grall
2015-07-09 20:42 ` [PATCH v2 03/20] xen/grant: Introduce helpers to split a page into grant Julien Grall
2015-07-16 15:01 ` Stefano Stabellini
2015-07-16 16:07 ` Julien Grall
2015-07-17 13:10 ` [Xen-devel] " Julien Grall
2015-07-09 20:42 ` [PATCH v2 04/20] xen/grant: Add helper gnttab_page_grant_foreign_access_ref Julien Grall
2015-07-16 15:05 ` Stefano Stabellini
2015-07-16 16:12 ` [Xen-devel] " Julien Grall
2015-07-24 9:35 ` David Vrabel
2015-07-09 20:42 ` [PATCH v2 05/20] block/xen-blkfront: Split blkif_queue_request in 2 Julien Grall
2015-07-21 9:54 ` Roger Pau Monné
2015-07-21 11:12 ` [Xen-devel] " Julien Grall
2015-07-09 20:42 ` [PATCH v2 06/20] block/xen-blkfront: Store a page rather a pfn in the grant structure Julien Grall
2015-07-16 15:11 ` Stefano Stabellini
2015-07-23 17:18 ` Julien Grall
2015-07-21 10:16 ` Roger Pau Monné
2015-07-21 11:19 ` [Xen-devel] " Julien Grall
2015-07-09 20:42 ` [PATCH v2 07/20] block/xen-blkfront: split get_grant in 2 Julien Grall
2015-07-21 10:30 ` Roger Pau Monné
2015-07-21 13:03 ` [Xen-devel] " Julien Grall
2015-07-09 20:42 ` [PATCH v2 08/20] net/xen-netback: xenvif_gop_frag_copy: move GSO check out of the loop Julien Grall
2015-07-09 20:42 ` [PATCH v2 09/20] xen/biomerge: Don't allow biovec to be merge when Linux is not using 4KB page Julien Grall
2015-07-10 19:12 ` Konrad Rzeszutek Wilk
2015-07-15 8:56 ` [Xen-devel] " Julien Grall
2015-07-16 15:33 ` Stefano Stabellini
2015-07-16 16:15 ` [Xen-devel] " Julien Grall
2015-07-16 18:30 ` Konrad Rzeszutek Wilk
2015-07-17 13:20 ` Stefano Stabellini
2015-07-17 14:44 ` Julien Grall
2015-07-17 14:45 ` Stefano Stabellini
2015-07-17 14:46 ` Julien Grall
2015-07-09 20:42 ` [PATCH v2 10/20] xen/xenbus: Use Xen page definition Julien Grall
2015-07-16 15:35 ` Stefano Stabellini
2015-07-24 9:49 ` David Vrabel
2015-07-09 20:42 ` [PATCH v2 11/20] tty/hvc: xen: Use xen " Julien Grall
2015-07-16 15:36 ` Stefano Stabellini
2015-07-24 9:52 ` David Vrabel
2015-07-09 20:42 ` [PATCH v2 12/20] xen/balloon: Don't rely on the page granularity is the same for Xen and Linux Julien Grall
2015-07-17 14:03 ` Stefano Stabellini
2015-07-17 14:32 ` Julien Grall
2015-07-09 20:42 ` [PATCH v2 13/20] xen/events: fifo: Make it running on 64KB granularity Julien Grall
2015-07-16 15:43 ` Stefano Stabellini
2015-07-16 16:18 ` [Xen-devel] " Julien Grall
2015-07-17 13:06 ` Stefano Stabellini
2015-07-24 10:36 ` David Vrabel
2015-08-06 15:43 ` [Xen-devel] " Julien Grall
2015-07-09 20:42 ` [PATCH v2 14/20] xen/grant-table: " Julien Grall
2015-07-16 15:47 ` Stefano Stabellini
2015-07-16 16:23 ` [Xen-devel] " Julien Grall
2015-07-17 13:37 ` Stefano Stabellini
2015-07-09 20:42 ` [PATCH v2 15/20] block/xen-blkfront: Make it running on 64KB page granularity Julien Grall
2015-07-21 11:06 ` Roger Pau Monné
2015-07-21 13:07 ` Julien Grall [this message]
2015-07-09 20:42 ` [PATCH v2 16/20] block/xen-blkback: " Julien Grall
2015-07-09 20:42 ` [PATCH v2 17/20] net/xen-netfront: " Julien Grall
2015-07-20 17:26 ` [Xen-devel] " Julien Grall
2015-07-09 20:42 ` [PATCH v2 18/20] net/xen-netback: " Julien Grall
2015-07-09 20:42 ` [PATCH v2 19/20] xen/privcmd: Add support for Linux " Julien Grall
2015-07-13 20:13 ` Boris Ostrovsky
2015-07-13 22:05 ` Julien Grall
2015-07-14 15:28 ` Boris Ostrovsky
2015-07-14 15:37 ` Julien Grall
2015-07-16 17:12 ` Stefano Stabellini
2015-07-16 17:16 ` Stefano Stabellini
2015-07-17 12:50 ` [Xen-devel] " Julien Grall
2015-07-09 20:42 ` [PATCH v2 20/20] arm/xen: Add support for " Julien Grall
2015-07-20 17:54 ` [Xen-devel] [PATCH v2 00/20] xen/arm64: Add support for 64KB page Julien Grall
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