From: Christoph Lameter <cl@gentwo.org>
To: Rustam Kovhaev <rkovhaev@gmail.com>
Cc: David Laight <David.Laight@aculab.com>,
'Vlastimil Babka' <vbabka@suse.cz>,
"penberg@kernel.org" <penberg@kernel.org>,
"rientjes@google.com" <rientjes@google.com>,
"iamjoonsoo.kim@lge.com" <iamjoonsoo.kim@lge.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"corbet@lwn.net" <corbet@lwn.net>,
"djwong@kernel.org" <djwong@kernel.org>,
"david@fromorbit.com" <david@fromorbit.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
"dvyukov@google.com" <dvyukov@google.com>
Subject: Re: [PATCH v4] slob: add size header to all allocations
Date: Tue, 30 Nov 2021 10:41:15 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2111301038150.291899@gentwo.de> (raw)
In-Reply-To: <YaXMBm4zUSTRUGx1@nuc10>
On Mon, 29 Nov 2021, Rustam Kovhaev wrote:
> > I'm not sure that helps.
> > The header can't share a cache line with the previous item (because it
> > might be mapped for DMA) so will always take a full cache line.
>
> I thought that DMA API allocates buffers that are larger than page size.
> DMA pool seems to be able to give out smaller buffers, but underneath it
> seems to be calling page allocator.
> The SLOB objects that have this header are all less than page size, and
> they cannot end up in DMA code paths, or can they?
kmalloc slab allocations must return dmaable memory. If the underlying
hardware can only dma to a cache line border then all objects must be
aligned that way.
next prev parent reply other threads:[~2021-11-30 9:41 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 21:23 [PATCH] xfs: use kmem_cache_free() for kmem_cache objects Rustam Kovhaev
2021-09-30 4:42 ` Dave Chinner
2021-09-30 8:13 ` Vlastimil Babka
2021-09-30 18:48 ` Rustam Kovhaev
2021-09-30 21:10 ` Vlastimil Babka
2021-10-01 0:32 ` Rustam Kovhaev
2021-10-04 1:07 ` David Rientjes
2021-10-12 20:43 ` Darrick J. Wong
2021-10-12 20:43 ` Darrick J. Wong
2021-10-12 21:32 ` Vlastimil Babka
2021-10-12 23:22 ` Darrick J. Wong
2021-10-13 7:38 ` Vlastimil Babka
2021-10-13 16:56 ` Rustam Kovhaev
2021-10-15 0:57 ` Darrick J. Wong
2021-10-18 3:38 ` [PATCH] slob: add size header to all allocations Rustam Kovhaev
2021-10-18 9:22 ` Vlastimil Babka
2021-10-19 1:22 ` Rustam Kovhaev
2021-10-20 11:46 ` Hyeonggon Yoo
2021-10-21 17:36 ` Vlastimil Babka
2021-10-23 6:41 ` [PATCH v2] " Rustam Kovhaev
2021-10-25 9:36 ` Vlastimil Babka
2021-10-25 21:49 ` Rustam Kovhaev
2021-10-29 3:05 ` [PATCH v3] " Rustam Kovhaev
2021-11-16 11:26 ` Vlastimil Babka
2021-11-16 23:19 ` Rustam Kovhaev
2021-11-22 1:30 ` [PATCH v4] " Rustam Kovhaev
2021-11-22 9:22 ` Christoph Lameter
2021-11-22 9:40 ` Vlastimil Babka
2021-11-22 10:36 ` Christoph Lameter
2021-11-22 10:45 ` Vlastimil Babka
2021-11-22 11:40 ` Christoph Lameter
2021-11-22 11:49 ` Vlastimil Babka
2021-11-23 10:18 ` David Laight
2021-11-30 7:00 ` Rustam Kovhaev
2021-11-30 9:23 ` David Laight
2021-11-30 9:41 ` Christoph Lameter [this message]
2021-11-30 14:55 ` Vlastimil Babka
2021-11-30 15:21 ` David Laight
2021-11-30 15:39 ` Vlastimil Babka
2021-11-30 15:26 ` Christoph Lameter
2021-10-24 10:43 ` [PATCH] " Hyeonggon Yoo
2021-10-25 8:19 ` Vlastimil Babka
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