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[146.241.108.137]) by smtp.gmail.com with ESMTPSA id q9-20020a1ce909000000b003f177c3672dsm6126552wmc.29.2023.04.20.13.23.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Apr 2023 13:23:15 -0700 (PDT) Message-ID: <98b96b354ef9e0b7cafb951b12988aee727807a3.camel@redhat.com> Subject: Re: [PATCH 0/3] softirq: uncontroversial change From: Paolo Abeni To: Eric Dumazet Cc: Jakub Kicinski , peterz@infradead.org, tglx@linutronix.de, jstultz@google.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 20 Apr 2023 22:23:14 +0200 In-Reply-To: References: <20221222221244.1290833-1-kuba@kernel.org> <305d7742212cbe98621b16be782b0562f1012cb6.camel@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.46.4 (3.46.4-1.fc37) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2023-04-20 at 19:41 +0200, Eric Dumazet wrote: > On Thu, Apr 20, 2023 at 7:24=E2=80=AFPM Paolo Abeni w= rote: > > I would like to propose a revert of: > >=20 > > 4cd13c21b207 softirq: Let ksoftirqd do its job > >=20 > > the its follow-ups: > >=20 > > 3c53776e29f8 Mark HI and TASKLET softirq synchronous > > 0f50524789fc softirq: Don't skip softirq execution when softirq thread = is parking > >=20 > > The problem originally addressed by 4cd13c21b207 can now be tackled > > with the threaded napi, available since: > >=20 > > 29863d41bb6e net: implement threaded-able napi poll loop support > >=20 > > Reverting the mentioned commit should address the latency issues > > mentioned by Jakub - I verified it solves a somewhat related problem in > > my setup - and reduces the layering of heuristics in this area. > >=20 > > A refactor introducing uniform overload detection and proper resource > > control will be better, but I admit it's beyond me and anyway it could > > still land afterwards. > >=20 > > Any opinion more then welcome! >=20 > Seems fine, but I think few things need to be fixed first in > napi_threaded_poll() > to enable some important features that are currently in net_rx_action() = only. Thanks for the feedback. I fear I'll miss some relevant bits.=C2=A0 On top of my head I think about RPS and skb_defer_free. Both should work even when napi threaded is enabled - with an additional softirq ;) Do you think we should be able to handle both inside the napi thread? Or do you refer to other features? Thanks! Paolo