Re: [RFC] pack-objects: compression level for non-blobs

> Add config pack.graphcompression similar to pack.compression.
> Applies to non-blob objects and if unspecified falls back to pack.compression.
> 
> We may identify objects compressed with level 0 by their leading bytes.
> Use this to force recompression when the source and target levels mismatch.
> Limit its application to when the config pack.graphcompression is set.
> 
> Signed-off-by: David Michael Barr <b@rr-dav.id.au (mailto:b@rr-dav.id.au)>
> ---
> builtin/pack-objects.c | 49 +++++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 45 insertions(+), 4 deletions(-)
> 
> I started working on this just before taking a vacation,
> so it's been a little while coming.
> 
> The intent is to allow selective recompression of pack data.
> For small objects/deltas the overhead of deflate is significant.
> This may improve read performance for the object graph.
> 
> I ran some unscientific experiments with the chromium repository.
> With pack.graphcompression = 0, there was a 2.7% increase in pack size.
> I saw a 35% improvement with cold caches and 43% otherwise on git log --raw.