Server load while cloning

[Matt Mackall]

On Wed, May 06, 2009 at 01:43:11PM -0700, Bryan O'Sullivan wrote:
> On Wed, May 6, 2009 at 9:42 AM, Greg Ward <greg-hg at gerg.ca> wrote:
> 
> > Specifically, using my desktop PC (3 GHz Pentium
> > 4, 2 GB RAM, 1 SATA disk) as the server and a different machine on the
> > LAN as client, cloning over HTTP takes ~7-9 minutes, during which the
> > server-side Mercurial process is above 80% CPU usage for most of the
> > time.  (It consumed about 6 min of CPU time during one clone.)
> >
> 
> Yep. Mercurial uses bzip2 compression for cloning over HTTP.

gzip is used for http
bzip2 is used for bundles
gzip is also used by ssh's compression layer

Most of the expense is -not- this stream compression, but the
decompression and full deltification of the data. When recompressed,
this greatly reduces our total bandwidth utilization.

-- 
Mathematics is the supreme nostalgia of our time.