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

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Jan 23, 2014 at 12:14:03PM -0800, Shawn Pearce wrote:

> > Yes, the mmap'd buffers aren't necessarily word-aligned. I don't think
> > we can fix that easily without changing the on-disk format (which comes
> > from JGit anyway).
> 
> Ouch, sorry about that. JGit doesn't mmap the file so we didn't think
> about the impact of words not being aligned. I should have caught
> that, but I didn't.

Looking over the format, I think the only thing preventing 4-byte
alignment is the 1-byte XOR-offset and 1-byte flags field for each
bitmap. If we ever have a v2, we could pad the sum of those out to 4
bytes. Is 4-byte alignment enough? We do treat the actual data as 64-bit
integers. I wonder if that would have problems on Sparc64, for example.

-Peff
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Kernel Development]     [Gcc Help]     [IETF Annouce]     [DCCP]     [Netdev]     [Networking]     [Security]     [V4L]     [Bugtraq]     [Yosemite]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux SCSI]     [Fedora Users]