From: Nadav Amit <nadav.amit@gmail.com>
To: Nicholas Piggin <npiggin@gmail.com>, Christoph Hellwig <hch@lst.de>
Cc: Rich Felker <dalias@libc.org>,
"David S. Miller" <davem@davemloft.net>,
James Hogan <jhogan@kernel.org>,
Paul Burton <paul.burton@mips.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Andrey Konovalov <andreyknvl@google.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Khalid Aziz <khalid.aziz@oracle.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mips@vger.kernel.org, Linux-MM <linux-mm@kvack.org>,
linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org,
Michael Ellerman <mpe@ellerman.id.au>,
Paul Mackerras <paulus@samba.org>,
sparclinux@vger.kernel.org,
the arch/x86 maintainers <x86@kernel.org>
Subject: Re: [PATCH 16/16] mm: pass get_user_pages_fast iterator arguments in a structure
Date: Tue, 11 Jun 2019 18:27:09 -0700 [thread overview]
Message-ID: <0441EC80-B09F-4722-B186-E42EB6A83386@gmail.com> (raw)
In-Reply-To: <1560300464.nijubslu3h.astroid@bobo.none>
> On Jun 11, 2019, at 5:52 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
>
> Christoph Hellwig's on June 12, 2019 12:41 am:
>> Instead of passing a set of always repeated arguments down the
>> get_user_pages_fast iterators, create a struct gup_args to hold them and
>> pass that by reference. This leads to an over 100 byte .text size
>> reduction for x86-64.
>
> What does this do for performance? I've found this pattern can be
> bad for store aliasing detection.
Note that sometimes such an optimization can also have adverse effect due to
stack protector code that gcc emits when you use such structs.
Matthew Wilcox encountered such a case:
https://patchwork.kernel.org/patch/10702741/
next prev parent reply other threads:[~2019-06-12 1:27 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-11 14:40 switch the remaining architectures to use generic GUP v3 Christoph Hellwig
2019-06-11 14:40 ` [PATCH 01/16] mm: use untagged_addr() for get_user_pages_fast addresses Christoph Hellwig
2019-06-11 19:22 ` Khalid Aziz
2019-06-21 13:16 ` Jason Gunthorpe
2019-06-21 13:39 ` Jason Gunthorpe
2019-06-21 15:35 ` Khalid Aziz
2019-06-21 15:54 ` Jason Gunthorpe
2019-06-25 7:41 ` Christoph Hellwig
2019-06-25 7:43 ` Christoph Hellwig
2019-06-11 14:40 ` [PATCH 02/16] mm: simplify gup_fast_permitted Christoph Hellwig
2019-06-21 13:40 ` Jason Gunthorpe
2019-06-11 14:40 ` [PATCH 03/16] mm: lift the x86_32 PAE version of gup_get_pte to common code Christoph Hellwig
2019-06-21 13:45 ` Jason Gunthorpe
2019-06-11 14:40 ` [PATCH 04/16] MIPS: use the generic get_user_pages_fast code Christoph Hellwig
2019-06-21 14:05 ` Jason Gunthorpe
2019-06-25 7:46 ` Christoph Hellwig
2019-06-11 14:40 ` [PATCH 05/16] sh: add the missing pud_page definition Christoph Hellwig
2019-06-11 14:40 ` [PATCH 06/16] sh: use the generic get_user_pages_fast code Christoph Hellwig
2019-06-11 14:40 ` [PATCH 07/16] sparc64: add the missing pgd_page definition Christoph Hellwig
2019-06-11 14:40 ` [PATCH 08/16] sparc64: define untagged_addr() Christoph Hellwig
2019-06-11 19:23 ` Khalid Aziz
2019-06-11 14:40 ` [PATCH 09/16] sparc64: use the generic get_user_pages_fast code Christoph Hellwig
2019-06-11 19:35 ` Khalid Aziz
2019-06-11 14:40 ` [PATCH 10/16] mm: rename CONFIG_HAVE_GENERIC_GUP to CONFIG_HAVE_FAST_GUP Christoph Hellwig
2019-06-11 19:35 ` Khalid Aziz
2019-06-21 14:28 ` Jason Gunthorpe
2019-06-25 7:50 ` Christoph Hellwig
2019-06-11 14:40 ` [PATCH 11/16] mm: consolidate the get_user_pages* implementations Christoph Hellwig
2019-06-21 14:41 ` Jason Gunthorpe
2019-06-25 7:56 ` Christoph Hellwig
2019-06-25 11:56 ` Jason Gunthorpe
2019-06-11 14:40 ` [PATCH 12/16] mm: validate get_user_pages_fast flags Christoph Hellwig
2019-06-11 14:40 ` [PATCH 13/16] mm: move the powerpc hugepd code to mm/gup.c Christoph Hellwig
2019-06-11 14:41 ` [PATCH 14/16] mm: switch gup_hugepte to use try_get_compound_head Christoph Hellwig
2019-06-11 14:41 ` [PATCH 15/16] mm: mark the page referenced in gup_hugepte Christoph Hellwig
2019-06-11 14:41 ` [PATCH 16/16] mm: pass get_user_pages_fast iterator arguments in a structure Christoph Hellwig
2019-06-12 0:52 ` Nicholas Piggin
2019-06-12 1:09 ` Linus Torvalds
2019-06-20 12:18 ` Nicholas Piggin
2019-06-20 17:21 ` Linus Torvalds
2019-06-21 8:15 ` Christoph Hellwig
2019-06-21 23:55 ` Nicholas Piggin
2019-06-21 8:29 ` Nicholas Piggin
2019-06-12 1:27 ` Nadav Amit [this message]
2019-06-20 11:45 ` switch the remaining architectures to use generic GUP v3 Christoph Hellwig
2019-06-21 14:43 ` Jason Gunthorpe
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