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Howlett" , Matthew Wilcox , David Rientjes , Christoph Lameter , Pekka Enberg , Joonsoo Kim , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Roman Gushchin Subject: Re: mm, slab/slub: Ensure kmem_cache_alloc_bulk() is available early In-Reply-To: <8b7762c3-02be-a5c9-1c4d-507cfb51a15c@suse.cz> References: <202302011308.f53123d2-oliver.sang@intel.com> <87o7qdzfay.ffs@tglx> <9a682773-df56-f36c-f582-e8eeef55d7f8@suse.cz> <875ycdwyx6.ffs@tglx> <871qn1wofe.ffs@tglx> <6c0b681e-97bc-d975-a8b9-500abdaaf0bc@suse.cz> <8b7762c3-02be-a5c9-1c4d-507cfb51a15c@suse.cz> Date: Tue, 07 Feb 2023 19:20:31 +0100 Message-ID: <87edr1uykw.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 63D581C0014 X-Stat-Signature: 78j7n7os5f9baiobn6px4wt5ifc46x3r X-HE-Tag: 1675794034-382647 X-HE-Meta: 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 aaulr3LE 6oOQS4NuXNYOcjnYBuxMLGgwdqmRuCOKtI2m8kmwsQ2l+LO3O4IB6zx+TqnCu6mjG4I/D4qaghhzkGYX8ovDG7TZH/pZjK72Tt/qQ12QA1tWNgmsC+K/CazQQe8vuOPNmwDzIf9hd00t36zFC5x73E/UjXYViNutuJiHB3iJsoVs4DUaO/WFXLFhKzWYZNLQcS2EW 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: On Tue, Feb 07 2023 at 15:47, Vlastimil Babka wrote: > From 340d7c7b99f3e67780f6dec480ed1d27e6f325eb Mon Sep 17 00:00:00 2001 > From: Vlastimil Babka > Date: Tue, 7 Feb 2023 15:34:53 +0100 > Subject: [PATCH] mm, slab/slub: remove notes that bulk alloc/free needs > interrupts enabled > > The slab functions kmem_cache_[alloc|free]_bulk() have been documented > as requiring interrupts to be enabled, since their addition in 2015. > It's unclear whether that was a fundamental restriction, or an attempt > to save some cpu cycles by not having to save and restore the irq > flags. I don't think so. The restriction is rather meant to avoid huge allocations in atomic context which causes latencies and also might deplete the atomic reserves. So I rather avoid that and enforce !ATOMIC mode despite the local_irq_save/restore() change which is really only to accomodate with early boot. Thanks, tglx