From: Alexander Duyck <alexander.duyck@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>,
Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
David Ahern <dsahern@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Jens Axboe <axboe@kernel.dk>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Jeroen de Borst <jeroendb@google.com>,
Catherine Sullivan <csully@google.com>,
Shailend Chand <shailend@google.com>,
Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
Sean Wang <sean.wang@mediatek.com>,
Mark Lee <Mark-MC.Lee@mediatek.com>,
Lorenzo Bianconi <lorenzo@kernel.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com>,
Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
Chaitanya Kulkarni <kch@nvidia.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org,
linux-nvme@lists.infradead.org
Subject: Re: [PATCH net-next 03/12] mm: Make the page_frag_cache allocator alignment param a pow-of-2
Date: Fri, 16 Jun 2023 09:06:19 -0700 [thread overview]
Message-ID: <CAKgT0Udfud_wVKLiZbi4Okuzor7OKzRi_PwvvCwnsiOdw7ir7A@mail.gmail.com> (raw)
In-Reply-To: <617059.1686929309@warthog.procyon.org.uk>
On Fri, Jun 16, 2023 at 8:28 AM David Howells <dhowells@redhat.com> wrote:
>
> Alexander H Duyck <alexander.duyck@gmail.com> wrote:
>
> > The requirement should only be cache alignment, not power of 2
> > alignment.
>
> Sure, but, upstream, page_frag_alloc_align() allows the specification of an
> alignment and applies that alignment by:
>
> offset &= align_mask;
>
> which doesn't really make sense unless the alignment boils down to being a
> power of two. Now, it might make sense to kill off the align_mask parameter
> and just go with SMP_CACHE_BYTES (which will be a power of two).
>
> Note, though, that most users seem to use an align_mask of ~0u which feels a
> bit dodgy (it's not an unsigned long), but is probably fine.
Yeah, now that I think about it this should be fine. I must have been
responding to this without enough sleep. When I originally read it I
saw it as limiting it to a power of 2 allocation, not limiting the
alignment mask to a power of 2.
next prev parent reply other threads:[~2023-06-16 16:07 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-24 15:32 [PATCH net-next 00/12] splice, net: Replace sendpage with sendmsg(MSG_SPLICE_PAGES), part 3 David Howells
2023-05-24 15:33 ` [PATCH net-next 01/12] mm: Move the page fragment allocator from page_alloc.c into its own file David Howells
2023-05-24 15:33 ` [PATCH net-next 02/12] mm: Provide a page_frag_cache allocator cleanup function David Howells
2023-05-24 15:33 ` [PATCH net-next 03/12] mm: Make the page_frag_cache allocator alignment param a pow-of-2 David Howells
2023-05-27 15:54 ` Alexander H Duyck
2023-11-30 9:00 ` Yunsheng Lin
2023-06-16 15:28 ` David Howells
2023-06-16 16:06 ` Alexander Duyck [this message]
2023-05-24 15:33 ` [PATCH net-next 04/12] mm: Make the page_frag_cache allocator use multipage folios David Howells
2023-05-26 11:56 ` Yunsheng Lin
2023-05-27 15:47 ` Alexander H Duyck
2023-05-26 12:47 ` David Howells
2023-05-26 14:06 ` Mika Penttilä
2023-05-27 0:50 ` Jakub Kicinski
2023-05-24 15:33 ` [PATCH net-next 05/12] mm: Make the page_frag_cache allocator handle __GFP_ZERO itself David Howells
2023-05-27 0:57 ` Jakub Kicinski
2023-05-27 15:54 ` Alexander Duyck
2023-05-24 15:33 ` [PATCH net-next 06/12] mm: Make the page_frag_cache allocator use per-cpu David Howells
2023-05-27 1:02 ` Jakub Kicinski
2023-05-24 15:33 ` [PATCH net-next 07/12] net: Clean up users of netdev_alloc_cache and napi_frag_cache David Howells
2023-05-24 15:33 ` [PATCH net-next 08/12] net: Copy slab data for sendmsg(MSG_SPLICE_PAGES) David Howells
2023-05-24 15:33 ` [PATCH net-next 09/12] tls/sw: Support MSG_SPLICE_PAGES David Howells
2023-05-27 1:08 ` Jakub Kicinski
2023-05-30 22:26 ` Bug in short splice to socket? David Howells
2023-05-31 0:32 ` Jakub Kicinski
2023-05-24 15:33 ` [PATCH net-next 10/12] tls/sw: Convert tls_sw_sendpage() to use MSG_SPLICE_PAGES David Howells
2023-05-27 1:13 ` Jakub Kicinski
2023-05-24 15:33 ` [PATCH net-next 11/12] tls/device: Support MSG_SPLICE_PAGES David Howells
2023-05-24 15:33 ` [PATCH net-next 12/12] tls/device: Convert tls_device_sendpage() to use MSG_SPLICE_PAGES David Howells
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