[Dovecot] 1.0(.14) vs 1.1.2 performance
Hello Timo,
I just switched from dovecot-1.0.14 to dovecot-1.1.2 and noticed a significant drop in the server load average (which has become lower and above all doesn't seem to have unexplained peaks). Indexes are still locally stored and nfs attribute caching is still off).
I searched the list archives for an explanation of what changed in the code that could explain such an improvement but mostly (except maybe some index code rewrite mentions) found differences in features.
Where does that performance gap come from ?
-- Thomas Hummel | Institut Pasteur hummel@pasteur.fr | Pôle informatique - systèmes et réseau
On Aug 5, 2008, at 9:43 AM, Thomas Hummel wrote:
I just switched from dovecot-1.0.14 to dovecot-1.1.2 and noticed a
significant drop in the server load average (which has become lower and above
all doesn't seem to have unexplained peaks). Indexes are still locally stored
and nfs attribute caching is still off).I searched the list archives for an explanation of what changed in
the code that could explain such an improvement but mostly (except maybe some
index code rewrite mentions) found differences in features.Where does that performance gap come from ?
Do you use POP3? That should work better. There are also less reads/
writes to index files. And dovecot-uidlist is usually updated by
appending to it instead of rewriting it.
On Tue, Aug 05, 2008 at 06:40:00PM -0400, Timo Sirainen wrote:
Do you use POP3?
Yes. I don't have the stats right now but I'd say, on 2500 users, 60% are using IMAP, 40% POP3.
But I had the feeling that it was the IMAP processes which were causing the load, particulary because some IMAP users were complaining about low speed while moving messages from mailboxes (I'm talking 1.0.14 here). However, I don't know if it was a cause or a consequence...
That should work better.
A lot indeed.
There are also less reads/ writes to index files. And dovecot-uidlist is usually updated by
appending to it instead of rewriting it.
So no big architectural changes ? Or maybe changes in the locking code ?
What about the upcomming 2.0 ? Is the new master expected to provide load improvement ?
Great work anyway ! ;-)
Thanks.
-- Thomas Hummel | Institut Pasteur hummel@pasteur.fr | Pôle informatique - systèmes et réseau
On Aug 6, 2008, at 4:56 AM, Thomas Hummel wrote:
On Tue, Aug 05, 2008 at 06:40:00PM -0400, Timo Sirainen wrote:
Do you use POP3?
Yes. I don't have the stats right now but I'd say, on 2500 users,
60% are using IMAP, 40% POP3.But I had the feeling that it was the IMAP processes which were
causing the load, particulary because some IMAP users were complaining about low
speed while moving messages from mailboxes (I'm talking 1.0.14 here).
However, I don't know if it was a cause or a consequence...
Well, one change is that by default copying messages is now done using
hard links, but you could have done that with v1.0 also by changing a
setting.
So no big architectural changes ? Or maybe changes in the locking code ?
Not really.
What about the upcomming 2.0 ? Is the new master expected to provide
load improvement ?
No. It's mostly about making the master more modular.
On Wed, Aug 06, 2008 at 10:30:09AM -0400, Timo Sirainen wrote:
Well, one change is that by default copying messages is now done using
hard links, but you could have done that with v1.0 also by changing a
setting.
Yes, that's what I did at the time I was running 1.0.14.
-- Thomas Hummel | Institut Pasteur hummel@pasteur.fr | Pôle informatique - systèmes et réseau
participants (2)
-
Thomas Hummel
-
Timo Sirainen