From: Isaac Manjarres <isaacmanjarres@google.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Christoph Hellwig <hch@lst.de>,
Robin Murphy <robin.murphy@arm.com>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Herbert Xu <herbert@gondor.apana.org.au>,
Saravana Kannan <saravanak@google.com>,
Alasdair Kergon <agk@redhat.com>, Daniel Vetter <daniel@ffwll.ch>,
Joerg Roedel <joro@8bytes.org>, Mark Brown <broonie@kernel.org>,
Mike Snitzer <snitzer@kernel.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Jonathan Cameron <jic23@kernel.org>,
linux-mm@kvack.org, iommu@lists.linux.dev,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v6 00/17] mm, dma, arm64: Reduce ARCH_KMALLOC_MINALIGN to 8
Date: Thu, 8 Jun 2023 14:29:45 -0700 [thread overview]
Message-ID: <ZIJISbauzCR/oKby@google.com> (raw)
In-Reply-To: <CAMj1kXHP_57EOOYQtuL2NO9=7sHPxrX=c0ayYwHaYx9x9hxhJw@mail.gmail.com>
On Thu, Jun 08, 2023 at 10:05:58AM +0200, Ard Biesheuvel wrote:
> On Thu, 8 Jun 2023 at 07:45, Isaac Manjarres <isaacmanjarres@google.com> wrote:
> >
> > On Wed, May 31, 2023 at 8:48 AM Catalin Marinas <catalin.marinas@arm.com> wrote:
> > > Here's version 6 of the series reducing the kmalloc() minimum alignment
> > > on arm64 to 8 (from 128). There are patches already to do the same for
> > > riscv (pretty straight-forward after this series).
> > Thanks, Catalin for getting these patches out. Please add my "Tested-by:" tag
> > for the series:
> >
> > Tested-by: Isaac J. Manjarres <isaacmanjarres@google.com>
> >
> > With the first 11 patches, I observed a reduction of 18.4 MB
> > in the slab memory footprint on my Pixel 6 device. After applying the
> > rest of the patches in the series, I observed a total reduction of
> > 26.5 MB in the
> > slab memory footprint on my device. These are great results!
> >
>
> It would also be good to get an insight into how much bouncing is
> going on in this case, given that (AFAIK) Pixel 6 uses non-cache
> coherent DMA.
I enabled the "swiotlb_bounced" trace event from the kernel command line
to see if anything was being bounced. It turns out that for Pixel 6
there are non-coherent DMA transfers occurring, but none of the
transfers that are in either the DMA_FROM_DEVICE or
DMA_BIDIRECTIONAL directions are small enough to require bouncing.
--Isaac
P.S. I noticed that the trace_swiotlb_bounced() tracepoint may not be
invoked even though bouncing occurs. For example, in the dma-iommu path,
swiotlb_tbl_map_single() is called when bouncing, instead of
swiotlb_map(), which is what ends up calling trace_swiotlb_bounced().
Would it make sense to move the call to trace_swiotlb_bounced() to
swiotlb_tbl_map_single() since that function is always invoked?
next prev parent reply other threads:[~2023-06-08 21:29 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-31 15:48 [PATCH v6 00/17] mm, dma, arm64: Reduce ARCH_KMALLOC_MINALIGN to 8 Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 01/17] mm/slab: Decouple ARCH_KMALLOC_MINALIGN from ARCH_DMA_MINALIGN Catalin Marinas
2023-06-09 12:32 ` Vlastimil Babka
2023-06-09 13:44 ` Catalin Marinas
2023-06-09 13:57 ` Catalin Marinas
2023-06-09 14:13 ` Vlastimil Babka
2023-05-31 15:48 ` [PATCH v6 02/17] dma: Allow dma_get_cache_alignment() to be overridden by the arch code Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 03/17] mm/slab: Simplify create_kmalloc_cache() args and make it static Catalin Marinas
2023-06-09 13:03 ` Vlastimil Babka
2023-05-31 15:48 ` [PATCH v6 04/17] mm/slab: Limit kmalloc() minimum alignment to dma_get_cache_alignment() Catalin Marinas
2023-06-09 14:33 ` Vlastimil Babka
2023-05-31 15:48 ` [PATCH v6 05/17] drivers/base: Use ARCH_DMA_MINALIGN instead of ARCH_KMALLOC_MINALIGN Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 06/17] drivers/gpu: " Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 07/17] drivers/usb: " Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 08/17] drivers/spi: " Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 09/17] dm-crypt: " Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 10/17] iio: core: " Catalin Marinas
2023-06-02 11:19 ` Jonathan Cameron
2023-05-31 15:48 ` [PATCH v6 11/17] arm64: Allow kmalloc() caches aligned to the smaller cache_line_size() Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 12/17] scatterlist: Add dedicated config for DMA flags Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 13/17] dma-mapping: Name SG DMA flag helpers consistently Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 14/17] dma-mapping: Force bouncing if the kmalloc() size is not cache-line-aligned Catalin Marinas
2023-05-31 15:48 ` [PATCH v6 15/17] iommu/dma: Force bouncing if the size is not cacheline-aligned Catalin Marinas
2023-06-09 11:52 ` Robin Murphy
2023-05-31 15:48 ` [PATCH v6 16/17] mm: slab: Reduce the kmalloc() minimum alignment if DMA bouncing possible Catalin Marinas
2023-06-09 14:39 ` Vlastimil Babka
2023-05-31 15:48 ` [PATCH v6 17/17] arm64: Enable ARCH_WANT_KMALLOC_DMA_BOUNCE for arm64 Catalin Marinas
2023-06-08 5:45 ` [PATCH v6 00/17] mm, dma, arm64: Reduce ARCH_KMALLOC_MINALIGN to 8 Isaac Manjarres
2023-06-08 8:05 ` Ard Biesheuvel
2023-06-08 21:29 ` Isaac Manjarres [this message]
2023-06-09 8:11 ` Petr Tesařík
2023-06-12 7:44 ` Tomonori Fujita
2023-06-12 7:47 ` Christoph Hellwig
2023-06-14 23:55 ` Isaac Manjarres
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