[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v4 03/16] libs/guest: Reduce number of I/O vectors in write_batch
- To: Frediano Ziglio <freddy77@xxxxxxxxx>
- From: Roger Pau Monné <roger.pau@xxxxxxxxxx>
- Date: Mon, 8 Jun 2026 17:03:53 +0200
- Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=citrix.com; dmarc=pass action=none header.from=citrix.com; dkim=pass header.d=citrix.com; arc=none
- Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=pFGTu9+V7Rn6EYMUbdRJEm1hVACMn8+NuVW5fk+egsM=; b=YZp50I3vfW9U3W2gQZnQeXBhplsA7A9yW5ghAq5kQHjql6gzZju5/MezI31GhPHIMDc4/AUTLCsOU+3KFVDdp3JRvqEyC1fc9vTQQo9nSnUiSbEV/koL+pvfgRXyoQK/gmiYu3xLoLqJxPW03vNOHsF2lcSk+BS/5c1xc5pJ4O3VhKm4OtAkcwlMHNZcqVTqm22c71PPl9dT6HXQCVlE8Di1MZTx5bFZN11dvG1vPFcXdGJkBvaGeBwIY4X4MF5LfAQFvxDLLx1eXuVw0lKygzVHY8p5/r008vL/2IX3SwpD+X/AwrbP++HjxOkiXxD3pUDfmbY6EvWXWPnr8kNoIg==
- Arc-seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=i6UJtGRNfaOjZi98UogIxbhARelb5t/rtMpbaT4cgxl16+CtJGlJbN2ykS+fovDgrQkw78T1gfxBNhg/dPB/ZLu6L03M621s4erYUQiiBbll7HL6GKVE8B9C7EcFYGte/AakhO0oc4DPZLFwSQGdwH/VwDIa1WuTb+1jvPiDBDD2C3f+14atxtWLlc9W3MHCSEiDea+HCqfVzToA5tQ8q1ITOUAjpyIXx1nLIvK4muy8zKAO2bHruvAPUmyzGB2LboueRU17app6tQloeLpszjJDPvjUpeG9n89Tm8mKHU7ynxgds9lVhb2I2TdkQiFyLjeNU3am/AaqaceAyaCBSQ==
- Authentication-results: eu.smtp.expurgate.cloud; dkim=pass header.s=selector1 header.d=citrix.com header.i="@citrix.com" header.h="From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck"
- Authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=citrix.com;
- Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx, Frediano Ziglio <frediano.ziglio@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Teddy Astie <teddy.astie@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>
- Delivery-date: Mon, 08 Jun 2026 15:04:15 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On Wed, Jun 03, 2026 at 02:05:50PM +0100, Frediano Ziglio wrote:
> From: Frediano Ziglio <frediano.ziglio@xxxxxxxxxx>
>
> Each page was sent using a different iovec item. This potentially exceed
> Linux maximum (1024).
> Also some implementation (MiniOS) emulate writev with multiple write calls.
I would add to the commit message:
"Coalesce adjacent IO vector elements to attempt to reduce the number
of overall IO vectors for each operation."
> Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxxx>
Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> --
> Changes since v2:
> - change prefix in subject.
> ---
> tools/libs/guest/xg_sr_save.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/tools/libs/guest/xg_sr_save.c b/tools/libs/guest/xg_sr_save.c
> index 1700d81905..62a39dfecc 100644
> --- a/tools/libs/guest/xg_sr_save.c
> +++ b/tools/libs/guest/xg_sr_save.c
> @@ -240,13 +240,20 @@ static int write_batch(struct xc_sr_context *ctx)
> {
> for ( i = 0; i < nr_pfns; ++i )
> {
> - if ( guest_data[i] )
> + if ( !guest_data[i] )
> + continue;
> +
> + if ( iov[iovcnt-1].iov_base + iov[iovcnt-1].iov_len !=
> guest_data[i] )
Nit: space between subtraction and operands: iovcnt - 1.
Thanks, Roger.
|
