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Fri, 06 Aug 2021 08:52:09 -0700 (PDT) MIME-Version: 1.0 References: <20210720232624.1493424-1-nitesh@redhat.com> <20210720232624.1493424-2-nitesh@redhat.com> In-Reply-To: <20210720232624.1493424-2-nitesh@redhat.com> From: Ming Lei Date: Fri, 6 Aug 2021 23:51:58 +0800 Message-ID: Subject: Re: [PATCH v5 01/14] genirq: Provide new interfaces for affinity hints To: Nitesh Narayan Lal Cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, linux-api@vger.kernel.org, linux-pci@vger.kernel.org, tglx@linutronix.de, jesse.brandeburg@intel.com, Robin Murphy , mtosatti@redhat.com, mingo@kernel.org, jbrandeb@kernel.org, frederic@kernel.org, juri.lelli@redhat.com, abelits@marvell.com, bhelgaas@google.com, rostedt@goodmis.org, peterz@infradead.org, davem@davemloft.net, akpm@linux-foundation.org, sfr@canb.auug.org.au, stephen@networkplumber.org, rppt@linux.vnet.ibm.com, chris.friesen@windriver.com, maz@kernel.org, nhorman@tuxdriver.com, pjwaskiewicz@gmail.com, sassmann@redhat.com, thenzl@redhat.com, Kashyap Desai , sumit.saxena@broadcom.com, shivasharan.srikanteshwara@broadcom.com, sathya.prakash@broadcom.com, sreekanth.reddy@broadcom.com, suganath-prabu.subramani@broadcom.com, James Smart , dick.kennedy@broadcom.com, jkc@redhat.com, faisal.latif@intel.com, shiraz.saleem@intel.com, tariqt@nvidia.com, ahleihel@redhat.com, kheib@redhat.com, borisp@nvidia.com, saeedm@nvidia.com, benve@cisco.com, govind@gmx.com, jassisinghbrar@gmail.com, ajit.khaparde@broadcom.com, sriharsha.basavapatna@broadcom.com, somnath.kotur@broadcom.com, nilal@redhat.com, tatyana.e.nikolova@intel.com, mustafa.ismail@intel.com, ahs3@redhat.com, leonro@nvidia.com, chandrakanth.patil@broadcom.com, bjorn.andersson@linaro.org, chunkuang.hu@kernel.org, yongqiang.niu@mediatek.com, baolin.wang7@gmail.com, poros@redhat.com, Ewan Milne , jejb@linux.ibm.com, "Martin K. Petersen" , _govind@gmx.com, kabel@kernel.org, viresh.kumar@linaro.org, Tushar.Khandelwal@arm.com, kuba@kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 21, 2021 at 7:26 AM Nitesh Narayan Lal wrote: > > From: Thomas Gleixner > > The discussion about removing the side effect of irq_set_affinity_hint() of > actually applying the cpumask (if not NULL) as affinity to the interrupt, > unearthed a few unpleasantries: > > 1) The modular perf drivers rely on the current behaviour for the very > wrong reasons. > > 2) While none of the other drivers prevents user space from changing > the affinity, a cursorily inspection shows that there are at least > expectations in some drivers. > > #1 needs to be cleaned up anyway, so that's not a problem > > #2 might result in subtle regressions especially when irqbalanced (which > nowadays ignores the affinity hint) is disabled. > > Provide new interfaces: > > irq_update_affinity_hint() - Only sets the affinity hint pointer > irq_set_affinity_and_hint() - Set the pointer and apply the affinity to > the interrupt > > Make irq_set_affinity_hint() a wrapper around irq_apply_affinity_hint() and > document it to be phased out. > > Signed-off-by: Thomas Gleixner > Signed-off-by: Nitesh Narayan Lal > Link: https://lore.kernel.org/r/20210501021832.743094-1-jesse.brandeburg@intel.com Reviewed-by: Ming Lei