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Date:   Wed, 12 Jun 2019 10:52:53 +1000
From:   Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH 16/16] mm: pass get_user_pages_fast iterator arguments in
 a structure
To:     Rich Felker <dalias@libc.org>,
        "David S. Miller" <davem@davemloft.net>,
        Christoph Hellwig <hch@lst.de>,
        James Hogan <jhogan@kernel.org>,
        Paul Burton <paul.burton@mips.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Yoshinori Sato <ysato@users.sourceforge.jp>
Cc:     Andrey Konovalov <andreyknvl@google.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Khalid Aziz <khalid.aziz@oracle.com>,
        linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
        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,
        x86@kernel.org
References: <20190611144102.8848-1-hch@lst.de>
        <20190611144102.8848-17-hch@lst.de>
In-Reply-To: <20190611144102.8848-17-hch@lst.de>
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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.

Thanks,
Nick
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