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From: Thomas Gleixner <tglx@linutronix.de>
To: Vlastimil Babka <vbabka@suse.cz>,
	kernel test robot <oliver.sang@intel.com>,
	Shanker Donthineni <sdonthineni@nvidia.com>
Cc: oe-lkp@lists.linux.dev, lkp@intel.com,
	linux-kernel@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
	Michael Walle <michael@walle.cc>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Hans de Goede <hdegoede@redhat.com>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	linux-mm@kvack.org, "Liam R. Howlett" <Liam.Howlett@oracle.com>,
	Matthew Wilcox <willy@infradead.org>,
	David Rientjes <rientjes@google.com>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Hyeonggon Yoo <42.hyeyoo@gmail.com>,
	Roman Gushchin <roman.gushchin@linux.dev>
Subject: Re: mm, slab/slub: Ensure kmem_cache_alloc_bulk() is available early
Date: Tue, 07 Feb 2023 19:20:31 +0100	[thread overview]
Message-ID: <87edr1uykw.ffs@tglx> (raw)
In-Reply-To: <8b7762c3-02be-a5c9-1c4d-507cfb51a15c@suse.cz>

On Tue, Feb 07 2023 at 15:47, Vlastimil Babka wrote:
> From 340d7c7b99f3e67780f6dec480ed1d27e6f325eb Mon Sep 17 00:00:00 2001
> From: Vlastimil Babka <vbabka@suse.cz>
> 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

  reply	other threads:[~2023-02-07 18:20 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-30  0:57 [PATCH 0/5] Increase the number of IRQ descriptors for SPARSEIRQ Shanker Donthineni
2023-01-30  0:57 ` [PATCH 1/5] genirq: Use hlist for managing resend handlers Shanker Donthineni
2023-01-31  8:59   ` Thomas Gleixner
2023-01-31 16:17     ` Shanker Donthineni
2023-01-31 17:06       ` Shanker Donthineni
2023-01-30  0:57 ` [PATCH 2/5] genirq: Allocate IRQ descriptors at boot time for !SPARSEIRQ Shanker Donthineni
2023-01-31  9:16   ` Thomas Gleixner
2023-01-31 16:41     ` Shanker Donthineni
2023-02-07 10:28       ` Thomas Gleixner
2023-01-30  0:57 ` [PATCH 3/5] genirq: Introduce two helper functions Shanker Donthineni
2023-01-31  9:20   ` Thomas Gleixner
2023-01-31 16:42     ` Shanker Donthineni
2023-01-30  0:57 ` [PATCH 4/5] genirq: Use the common function irq_expand_nr_irqs() Shanker Donthineni
2023-01-31  9:35   ` Thomas Gleixner
2023-01-31 16:43     ` Shanker Donthineni
2023-02-07 10:29       ` Thomas Gleixner
2023-01-30  0:57 ` [PATCH 5/5] genirq: Use the maple tree for IRQ descriptors management Shanker Donthineni
2023-01-31  9:52   ` Thomas Gleixner
2023-01-31 16:45     ` Shanker Donthineni
2023-02-01  6:02   ` kernel test robot
2023-02-01 13:27     ` Thomas Gleixner
2023-02-06 14:24       ` Vlastimil Babka
2023-02-06 18:10         ` Thomas Gleixner
2023-02-07 10:30         ` Thomas Gleixner
2023-02-07 14:16           ` mm, slab/slub: Ensure kmem_cache_alloc_bulk() is available early Thomas Gleixner
2023-02-07 14:45             ` Vlastimil Babka
2023-02-07 14:47               ` Vlastimil Babka
2023-02-07 18:20                 ` Thomas Gleixner [this message]
2023-02-08  9:15                   ` Vlastimil Babka
2023-02-08 20:46                     ` Thomas Gleixner
2023-02-09 20:28                       ` Matthew Wilcox
2023-02-09 23:19                         ` Thomas Gleixner
2023-02-08 13:20             ` Hyeonggon Yoo

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