Re: [Pan-devel] Re: CVS version and download speed

[Mark H. Kraml]

I have noticed this slowdown also.

When getting smallish jpg files the slowdown is almost 50%, When getting
larger rar (5-15MB) files the slowdown is around 10%.

When decoding and saving monster 50-100MB files download actually stops
for the duration of the decode and save operation.

I suspect this is all because of the new single thread model used by the
program. On a slow network connections this would not be so bad, but
faster networks will fill up TCP windows and block during disk I/O.

mk

On Mon, 2005-10-03 at 01:33 -0700, Duncan wrote:
> Tom Dexter posted
> <address@hidden>, excerpted
> below,  on Sun, 02 Oct 2005 10:59:37 -0500:
> 
> > 
> > I mentioned this in an email to the list a few months ago, and was curious
> > if anyone else has noticed this.
> > 
> > I have a cable modem and normally get close to full 10 Mbps downloads.
> > With the 0.14.2 verions of pan I can generally get my full bandwidth when
> > downloading...800 KB/sec to over 1 MB/sec.  With the current CVS (and the
> > one from several months ago) it simply seems incapable of exceeding 300
> > KB/sec, often staying around 100-200.
> > 
> > This is compiled on an x86 system running the latest Gentoo (2.6 kernel).
> > Any suggestions would be appreciated.
> 
> The CVS version is a SERIOUS rewrite of the back-end.  It now uses less
> memory and does some other things differently, but will take a bit more
> CPU while downloading.  You don't say what sort of CPU you are running,
> but take a look at CPU usage and see if it's running high.  If so, that's
> your problem.
> 
> I'm not running CVS here, and AM running a dual Opteron (amd64, Gentoo
> here, too =8^), so even if I was, my numbers wouldn't mean much for you.
> However, taking a wild guess, if your CPU is say a 1.5GHz or slower, it's
> possible that's it.
> 
> Also note that the download method has been reworked some as well.  I
> don't believe it's using libgnet as the release versions do.  That may
> also be an issue, depending on how many download threads to how many news
> servers you are running.  Again, I'm not running CVS so I can't say how
> /much/ different it is in practice, but double-check that you have it
> configured for the correct amount of download threads (up to four per
> server allowed in the release versions, don't know about CVS).  It's
> possible you were running multiple threads before, and it's either
> configured for only one or two, now, or it's configured right but the new
> code may not be well optimized or may be buggy.
> 
> Finally, check your CFLAGS.  (Gentoo specific) Note that compiling from
> CVS will bypass the CFLAGS you have set in make.conf, since it's not
> compiling thru portage. You'll probably want to manually set a shell
> variable with your preferred CFLAGS, before compiling anything outside of
> portage, so you still get the ones you want.  (Also note that since you
> are compiling outside portage, you won't have portage filtering anything
> out of CFLAGS that's known not to work on a particular package, so
> consider scaling back a bit if something breaks.)
>