From: Andrew Morton <akpm@linux-foundation.org>
To: Zhaoxiu Zeng <zhaoxiu.zeng@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>,
George Spelvin <linux@horizon.com>,
David Howells <dhowells@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
Josh Boyer <jwboyer@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] GCD: add binary GCD algorithm
Date: Fri, 22 Aug 2014 14:31:17 -0700 [thread overview]
Message-ID: <20140822143117.29474ac2ac8092e27d26660a@linux-foundation.org> (raw)
In-Reply-To: <1408106956-12986-1-git-send-email-zhaoxiu.zeng@gmail.com>
On Fri, 15 Aug 2014 20:49:16 +0800 Zhaoxiu Zeng <zhaoxiu.zeng@gmail.com> wrote:
> Because some architectures (alpha, armv6, etc.) don't provide hardware division,
> the mod operation is slow! Binary GCD algorithm uses simple arithmetic operations,
> it replaces division with arithmetic shifts, comparisons, and subtraction.
I had a look around and it seems that most (all?) gcd() and lcd()
callers are on initialization-time slowpaths.
Do you know of a workload which will significantly benefit from this
change? If so, by how much?
Otherwise I don't think we can justify the additional maintenance
cost/risk, sorry.
And if we *do* decide to proceed with this patch, we should include a
patch which enables it on as many architectures as possible, so it gets
runtime tested.
next prev parent reply other threads:[~2014-08-22 21:31 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-15 12:49 Zhaoxiu Zeng
2014-08-15 13:58 ` Peter Zijlstra
2014-08-15 16:41 ` zhaoxiu.zeng
2014-08-15 21:53 ` George Spelvin
2014-08-15 20:16 ` George Spelvin
2014-08-15 21:32 ` Peter Zijlstra
2014-08-22 21:31 ` Andrew Morton [this message]
2014-08-22 22:36 ` George Spelvin
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