Re: auto gc again

On Wed, 19 Mar 2008, Junio C Hamano wrote:

Nicolas Pitre [off-list ref] writes:

quoted

On Wed, 19 Mar 2008, Junio C Hamano wrote:

quoted

I do not think "very tight" was the reason, but on the other hand, my
personal feeling is that 20 was already 10 too many pack idx files we have
to walk linearly while looking for objects at runtime.

Since commit f7c22cc68ccb this is no longer such an issue.

Notice that I did not say "19 too many".  I know f7c22cc (always start
looking up objects in the last used pack first, 2007-05-30) was meant to
alleviate the situation, but isn't "no longer" a gross exaggeration?

Not at all.  Please have a second look at the performance numbers in 
that commit log, and take into accound the most important metric that I 
unfortunately failed to mention there (although I subsequently posted it 
to the list: http://marc.info/?l=git&m=118058197921642&w=2), wich is the 
time to perform the same operation with a single pack.

So you have 17.1 seconds for a single pack vs 18.4 seconds for 66 packs.

Compare that to 24.9s without that patch.

And I still have some further optimizations to implement eventually 
(http://marc.info/?l=git&m=118062793413099&w=2), but which would 
probably make a significant difference only in the hundreds-of-packs 
case anyway.

So I really think that the default gc.autopacklimit could be raised.


Nicolas