Re: [dm-devel] [PATCH 1/2] multipath.conf(5): remove io-affinity information

From: Xose Vazquez Perez <xose.vazquez@gmail.com>
To: Benjamin Marzinski <bmarzins@redhat.com>
Cc: DM-DEVEL ML <dm-devel@redhat.com>, Martin Wilck <mwilck@suse.com>,
	Mike Christie <michael.christie@oracle.com>
Subject: Re: [dm-devel] [PATCH 1/2] multipath.conf(5): remove io-affinity information
Date: Sat, 3 Dec 2022 16:10:56 +0100	[thread overview]
Message-ID: <41d2ff77-05c8-dd18-b24f-e3ec6884dfb2@gmail.com> (raw)
In-Reply-To: <1669784208-9754-1-git-send-email-bmarzins@redhat.com>

On 11/30/22 05:56, bmarzins at redhat.com (Benjamin Marzinski) wrote:

> The multpath-tools do not support the io-affinity path selector.  We
> always add a repeat count as the path argument. The io-affinity selector
> doesn't take one. Instead it takes a bitmap of CPUs that a path can run
> on. This isn't something that lends itself to the kind of
> auto-assembling that multipathd does. But even if we did want to try to
> support this path-selector, until we do, we shouldn't be listing it in
> the multipath.conf documentation.
> 
> Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>

> ---
>   multipath/multipath.conf.5 | 4 ----
>   1 file changed, 4 deletions(-)
> 
> diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5
> index 1fea9d5a..3a45ac89 100644
> --- a/multipath/multipath.conf.5
> +++ b/multipath/multipath.conf.5
> @@ -205,10 +205,6 @@ of outstanding I/O to the path and its relative throughput.
>   estimation of future service time based on the history of previous I/O submitted
>   to each path.
>   .TP
> -.I "io-affinity 0"
> -(Since 5.11 kernel) Choose the path for the next bunch of I/O based on a CPU to
> -path mapping the user passes in and what CPU we are executing on.
> -.TP
>   The default is: \fBservice-time 0\fR
>   .RE
>   .

I think the main, and only?, consumer for this path selector is Exadata.

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