Re: Mercurial's only true "plugin" extension: inotify... and can it be done in Git?

From: J. Bruce Fields <bfields@fieldses.org>
Date: Mar 10, 2008, 22:58 UTC
Message-ID: <20080310225821.GS13660@fieldses.org>
In-Reply-To: <20080310224318.GC8410@spearce.org>

On Mon, Mar 10, 2008 at 06:43:18PM -0400, Shawn O. Pearce wrote:

> I think the reason Git has never had such an "extension" is we are
> just that freaking fast when it comes to comparing the working tree
> to the index.

NFS is an exception there; a git diff takes about 12 seconds for me. It's easy to see why--ping time to the server is about a quarter of a millisecond, so with some 24000 files to stat, and a roundtrip to the server required for each, it would take at least 6 seconds even if there was no other contribution to the stat latency.

But of course there's not much by way of file change notifications in the current NFS protocol either, so that doesn't help.

At some point I tried patching git to do the stat's in parallel (the totally lazy way--instead of modifying the existing code I just did an extra parallel stat of everything first, then threw the results away, so the real work would be done with a hot cache on the client). I could get it down to about 3.5 seconds that way, better though still annoying.

--b.