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From: David Turner <dturner@twopensource.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Michael Haggerty <mhagger@alum.mit.edu>,
	git@vger.kernel.org, David Turner <dturner@twitter.com>
Subject: Re: [PATCH v5 2/2] refs.c: SSE4.2 optimizations for check_refname_component
Date: Tue, 03 Jun 2014 23:35:11 -0400	[thread overview]
Message-ID: <1401852911.18134.134.camel@stross> (raw)
In-Reply-To: <xmqqd2epwsw0.fsf@gitster.dls.corp.google.com>

On Tue, 2014-06-03 at 15:05 -0700, Junio C Hamano wrote:
> > +		if (((uintptr_t) vp & (PAGE_SIZE - 1)) > PAGE_SIZE - BLOCK_SIZE)
> > +			/* End-of-page; fall back to slow method for
> > +			 * this entire component. */
> > +			return check_refname_component_1(refname, flags);
> 
> It is somewhat sad that we have to redo the whole thing, but nobody
> higher in the callchain knows how long the refname will be before
> calling us, so this cannot be avoided.

It actually could be avoided; we could pass in some extra args that let
check_refname_component_1 start checking after the part that we have
already checked.  I decided not to do this because I believe that
the average refname component is short, which means that the cost is not
too high and that it won't happen very often.  But I would be willing to
change this if you would like.

  reply	other threads:[~2014-06-04  3:35 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-02  6:20 [PATCH v5 1/2] refs.c: optimize check_refname_component() David Turner
2014-06-02  6:20 ` [PATCH v5 2/2] refs.c: SSE4.2 optimizations for check_refname_component David Turner
2014-06-03 22:05   ` Junio C Hamano
2014-06-04  3:35     ` David Turner [this message]
2014-06-03 18:08 ` [PATCH v5 1/2] refs.c: optimize check_refname_component() Junio C Hamano
  -- strict thread matches above, loose matches on Subject: below --
2014-06-03 18:21 David Turner
2014-06-03 18:21 ` [PATCH v5 2/2] refs.c: SSE4.2 optimizations for check_refname_component David Turner

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