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Mon, 15 Jun 2026 10:56:45 -0400 Received: (from bmarzins@localhost) by bmarzins-01.fast.eng.rdu2.dc.redhat.com (8.18.1/8.18.1/Submit) id 65FEujIi790626; Mon, 15 Jun 2026 10:56:45 -0400 Date: Mon, 15 Jun 2026 10:56:45 -0400 From: Benjamin Marzinski To: Martin Wilck Cc: Xose Vazquez Perez , Christophe Varoqui , DM_DEVEL-ML Subject: Re: [PATCH 1/3] multipath-tools: delete obsolete information from multipath.conf.5 Message-ID: References: <20260607103831.336833-1-xose.vazquez@gmail.com> <20260607103831.336833-2-xose.vazquez@gmail.com> <562d0c52ef13cfc1f8dec3c59b05b56304ce2c02.camel@suse.com> Precedence: bulk X-Mailing-List: dm-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <562d0c52ef13cfc1f8dec3c59b05b56304ce2c02.camel@suse.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: auhS-nraoBrTtptTjzc_JocpWWR7k2ar6wMJrXWvYTM_1781535407 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit On Mon, Jun 15, 2026 at 11:11:07AM +0200, Martin Wilck wrote: > On Sun, 2026-06-07 at 12:38 +0200, Xose Vazquez Perez wrote: > > repeat_count (rr_min_io, rr_min_io_rq, rr_weight) has been > > unsupported > > since kernel 4.6 ( commits 90a4323ccfea and  21136f89d76d ). > > > > I can't make up my mind on this patch. It is true that most path > selectors in the kernel have ignored the repeat_count argument > for a long time (historical_service_time still seems to honour it). > > But this is multipath-tools. _We_ still have quite a bit of code for > handling the minio and weight settings. We should add a hint the the > man page that these settings are ignored by modern kernels, but it > would be simply wrong to say that _our_ code ignores them while it > doesn't. > > We can decide to remove this functionality from multipath-tools, which > would obviously mean removing it from the man page as well. But if we > do, we should apply further cleanups. I suppose that providing the > "weightedpath" prioritizer makes no sense if we have no path selector > algorithm that takes such weights into account, for example. > > I should also note that there have been discussions with some partners > about re-introducing parameterized path selectors. This was a topic in > the context of Fibre Channel FPIN notifications: FPINs can be used by > FC fabric to notify hosts about overloaded paths. With a parameterized > path selector, the load on such paths could be decreased by multipathd. > temporarily until the situation is normal again. While there has been > little progress in this area, I don't consider it cast in stone that > the kernel will keep ignoring path selector parameters forever, or IOW, > that there won't be new path selectors in the future that do accept > path parameters again. > > No doubt that the way these parameters are interpreted in different > ways ("minio" vs. "weight" vs "repeat_count") and the way this is > exposed to end users in the configuration file and in the man page is > broken and confusing. But fixing that would be a larger effort. I actually do have a patch set I'm testing that rips out the rr_weight and rr_min_io_rq code completely. It leaves the rr_min_io functionality (on the grounds that we many have a use for it later), but it now defaults to 1 and is deprecated, so it can't be changed. I assume that even if this code gets reused in the future, rr_min_io will remain a bad name for the option. I feel like the weightedpath priortizer shouldn't be effected by this. It is still useful to manually assign paths to path_groups when combined with group_by_prio. -Ben > > Regards > Martin