[Gnu-arch-users] [PATCH] arch speedups on big trees

[Chris Mason]

Hello everyone,

I've been playing around with a few ideas to improve arch performance on
large source trees, mostly in the area of applying changesets, and
creating changesets.  I've got a sample archive here with 100 changesets
on top of the linux 2.6 kernel, and vanilla arch takes  a number of
minutes to apply them all (15-30 seconds per changeset via tla replay)

This is primarily because arch is doing an inventory of the source tree
before each changeset, my patch changes things to inventory only the
files touched by the changeset instead.  It sends a table of the
candidate files to the inventory funcs, and this brings the time to
replay my 100 changesets to ~4 seconds.

tla commit --file-list will also use a limited inventory, although it is
not as fast as it could be due to inode signatures and pristine tree
updates, I might work on a --quick option for tla commit that skips all
of that.

The patch also adds --link for make-pristine, I tend to make a number of
temporary trees while merging patches, it's easier to prevent revision
library creep if the hard linked trees get blown away with the rest of
the temp stuff.  The two changes are easy to distinguish, so I'm leaving
it as a single patch for now.

This is lightly tested (make test and a few others), don't use this on
trees you care about yet.  I'm new to the arch source and could be
missing a few things.

-chris

arch-faster.diff
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