dovecot - Oct 2011 - Thunderbird slow in talking with dovecot IMAP AND to sendmail

I'm trying to find out what's causing this slowdown -- it's
INTOLERABLE....

over 1 minute and less than 1% done. (400MB file)...

After trying 3 times, I gave up and logged in using X to the server and 
ran Tbird from there....

Mail sent out in < 1 minute, though the copy to dovecot took about 50% 
longer.

So...

I looked at the network trace.

and everyfrackin' body was using 4K packet sizes (at the application 
level!, the window size on TCP was over 64K...but no one was using 
it)....especially galling with my network's MTU at 9K, BTW, because
small packets are really bad on a 1Gb network.

sendmail -- 4K,
dovecot /ssl, 4K...

wazzup .. is t-bird forcing this, or is there some ssl requirement?

but it can't just be ssl -- as it's talking to sendmail on port 25 
unencrypted (it's a local
net anyway)...

I could see the entire binary going out in text form...

1 line at a time...a "C" line in sendmail, with lens of 4096...is that
some max?

I don't see it in the sendmail.cf files...wanted to see if anyone knew 
of dovecot restrictions that
might limit packets to 4k, before I lamblasted the thunderbird people 
for another act of mindless
stupidity  (the first being when they decided to cache all your IMAP 
store on every local client
in the client's ROAMING profile...*brilliant*!!!...

sides, if I  wanted it on local I would have set 'store on local', but 
in TB3, they know better
and change that for me...

Something about them being too stupid to use indexing and searching on 
an imap server?  Maybe I
just imagined hearing that...

On 2011-10-25 6:14 AM, Linda Walsh <dovecot at tlinx.org>
wrote:
> and everyfrackin' body was using 4K packet sizes (at the application
> level!, the window size on TCP was over 64K...but no one was using
> it)....especially galling with my network's MTU at 9K, BTW, because
> small packets are really bad on a 1Gb network.
>
> sendmail -- 4K,
> dovecot /ssl, 4K...
>
> wazzup .. is t-bird forcing this,
If I'm not mistaken, yes, this is (or could be) a TBird problem... I 
can't find the bug report where this was discussed, but I distinctly 
remember one of the devs commenting on this 4k packet size issue. 
Apparently it was an intentional change, but he couldn't figure out why.

Fyi, it was discussed in one of the IMAP performance bugs...

-- 

Best regards,

Charles

On 25/10/2011 11:14, Linda Walsh wrote:
>
>
> I'm trying to find out what's causing this slowdown -- it's
> INTOLERABLE....
>
> over 1 minute and less than 1% done. (400MB file)...
>
> After trying 3 times, I gave up and logged in using X to the server
> and ran Tbird from there....
>
> Mail sent out in < 1 minute, though the copy to dovecot took about 50%
> longer.
>
> So...
>
> I looked at the network trace.
>
> and everyfrackin' body was using 4K packet sizes (at the application
> level!, the window size on TCP was over 64K...but no one was using
> it)....especially galling with my network's MTU at 9K, BTW, because
> small packets are really bad on a 1Gb network.
>
Although larger packets might be helpful, I don't see that you shouldn't
be getting much faster speed without it?  Even the 64K window, whilst it
looks too small, might be ok if your ping times are very low?

Something else is limiting your performance I think?

Ed W