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AJvYcCWXm+JW7riOytFQ1YVAmI2Z710mwv+nMrbsR+1kG9cASz2CGR7gO8VxORZ9ohbwffiXKKkzUX9ebQ==@kvack.org X-Gm-Message-State: AOJu0Yze2ttt4JZlRx1h9xpV5BQw/tBZbMz7um0yL5An4gAS4fPuDIkU hP9T0zcRWGkkkl3zEDT+ss7BJqFRxAmQcOpuIpaL01nsfrkQ0+o8cT43XGawfygQTPLWvuLA1N2 sxjafczjiQqrK7vHi8moYQZjm0jbPioKlshE7Czws X-Gm-Gg: ASbGncvCYqFENOSihzKBM5DW+0bYFG6aerjYKFiooHIc9bnARcIxBLLLtfbZRgX8G0I HMKywwNj9DnB2xm86hdXcpag6AE9PS1oBwyuzob6X2iqZEK89fi9P5AW5TLM+nqLoOCZxGuwmn1 UANL+tZzWPJ6eZPC1crabcBW+NBF6nz9QT2vR4KnJNXgJAi5WeMU5+asLkALP/dTZME3g6SVg2N B4Qy/AWGPks X-Google-Smtp-Source: AGHT+IFie57Mb7sKx4CUZ5qKsCQeoeNOTrEmPRiPoBnlLAWdzMBBoHnVt4sefNukmoViqBJmoJjKbHzT5xDU0mO3fA8= X-Received: by 2002:ac8:7c4b:0:b0:4cf:dc5c:8c76 with SMTP id d75a77b69052e-4dec6c15531mr179221cf.11.1758901316443; Fri, 26 Sep 2025 08:41:56 -0700 (PDT) MIME-Version: 1.0 References: <20250910-slub-percpu-caches-v8-0-ca3099d8352c@suse.cz> <20250910-slub-percpu-caches-v8-4-ca3099d8352c@suse.cz> <6f92eca3-863e-4b77-b2df-dc2752c0ff4e@suse.cz> <40461105-a344-444f-834b-9559b6644710@suse.cz> <80f8bdf8-ce50-4682-9468-9f38e0817e89@suse.cz> In-Reply-To: <80f8bdf8-ce50-4682-9468-9f38e0817e89@suse.cz> From: Suren Baghdasaryan Date: Fri, 26 Sep 2025 08:41:45 -0700 X-Gm-Features: AS18NWARWDrEtqEv7CROqpWdTroNvRVXVK4eBsZm2RsgspwIkCZ14ujtVqZ6vgg Message-ID: Subject: Re: [PATCH v8 04/23] slab: add sheaf support for batching kfree_rcu() operations To: Vlastimil Babka Cc: Harry Yoo , "Liam R. Howlett" , Christoph Lameter , David Rientjes , Roman Gushchin , Uladzislau Rezki , Sidhartha Kumar , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, "Paul E . McKenney" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 2A49A20010 X-Stat-Signature: uoi4q7t5epzp6y176o56uwajtg5kyqni X-Rspam-User: X-HE-Tag: 1758901317-54404 X-HE-Meta: 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 kfLWWPOI wsHdHbF8I5+/RQg9MsNNm+ulnpZsjT2i5zErovgLZDVZ7rwU02oQFd0jMsSlNFhKAoNaGxLbBOTXWDN1ZwRaNH54FHNtmtwAQze0IaTNCsh4ktbjtnAvLAaFSEB2Qa6/sJaNp68XUo05xfBN4uh6qhAB64pP9yt3RzWXEYuAC0ogI2DdcOoTlcvfgsCIneihm0bHg/4PQyC1THE0tVR2BRekicn7euqWrJp56 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Sep 26, 2025 at 3:08=E2=80=AFAM Vlastimil Babka wr= ote: > > On 9/25/25 06:35, Suren Baghdasaryan wrote: > > On Thu, Sep 18, 2025 at 1:09=E2=80=AFAM Vlastimil Babka wrote: > >> > >> Expected advantages: > >> - batching the kfree_rcu() operations, that could eventually replace t= he > >> existing batching > >> - sheaves can be reused for allocations via barn instead of being > >> flushed to slabs, which is more efficient > >> - this includes cases where only some cpus are allowed to process rc= u > >> callbacks (Android) > > > > nit: I would say it's more CONFIG_RCU_NOCB_CPU related. Android is > > just an instance of that. > > OK changed that. > > Changes due to your other suggestions: > > diff --git a/mm/slub.c b/mm/slub.c > index 8220ce095970..fec0cdc7ef37 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -3945,15 +3945,12 @@ void flush_all_rcu_sheaves(void) > */ > > INIT_WORK(&sfw->work, flush_rcu_sheaf); > - sfw->skip =3D false; > sfw->s =3D s; > queue_work_on(cpu, flushwq, &sfw->work); > } > > for_each_online_cpu(cpu) { > sfw =3D &per_cpu(slub_flush, cpu); > - if (sfw->skip) > - continue; > flush_work(&sfw->work); > } > > @@ -5643,6 +5640,10 @@ bool __kfree_rcu_sheaf(struct kmem_cache *s, void = *obj) > > rcu_sheaf =3D pcs->rcu_free; > > + /* > + * Since we flush immediately when size reaches capacity, we neve= r reach > + * this with size already at capacity, so no OOB write is possibl= e. > + */ Perfect! Reviewed-by: Suren Baghdasaryan > rcu_sheaf->objects[rcu_sheaf->size++] =3D obj; > > if (likely(rcu_sheaf->size < s->sheaf_capacity)) >