Re: [PATCH v4 08/23] ewah: compressed bitmap implementation

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Jan 23, 2014, 22:33 UTC
Message-ID: <20140123223318.GB18964@google.com>
In-Reply-To: <20140123222632.GA2311@sigill.intra.peff.net>

Jeff King wrote:

> On Thu, Jan 23, 2014 at 02:17:55PM -0800, Jonathan Nieder wrote:

Show 6 quoted lines

>> I don't think that's a big issue.  A pair of 4-byte reads would not be
>> too slow.
>
> The header is actually two separate 4-byte values, so that's fine. But
> between the header and trailer are a series of 8-byte data values, and
> that is what we need the 8-byte alignment for.

Sorry for the lack of clarity. What I meant is that a 4-byte aligned 8-byte value can be read using a pair of 4-byte reads, which is less of a performance issue than a completely unaligned value.

[...]

> Anyway, this is all academic until we are designing bitmap v2, which I
> do not plan on doing anytime soon.

Sure, fair enough. :)

Jonathan