faster delivery of cyrus imap -- writev() takes 1.2 sec!

[Su Li]

If I send this message the second time. Please igore it.

Can you be more specific which directory Cyrus uses to sync? Does it have
some thing to do with duplicate delivery mode? 


Thanks a lot,


Su


-----Original Message-----
From: David Lang [mailto:dlang at diginsite.com]
Sent: September 8, 2002 12:11 AM
To: Su Li
Cc: info-cyrus at andrew.cmu.edu
Subject: Re: faster delivery of cyrus imap -- writev() takes 1.2 sec!


did you change the directories that cyrus uses to be synced for every
write? while that provides extra crash protection is slows things down a
LOT.

David Lang

 On Sat, 7 Sep 2002, Su Li wrote:

> Date: Sat, 7 Sep 2002 23:23:20 -0400
> From: Su Li <sli at rim.net>
> To: info-cyrus at andrew.cmu.edu
> Subject: faster delivery of cyrus imap -- writev() takes 1.2 sec!
>
> Hi,
>
> I tried to make Cyrus imap deliver mail faster, by changing
> --with-duplicated-db to skiplist and disabled notification. It didn't
work.
> I am sending email from my testing tool. I run 4 of them, each trying to
> send one email to mail server with a delay of 20 msec. It seems the Cyrus
> imap can only process 1 email per second.
>
> My configuration for imap is:
>
> ./configure --with-auth=unix --without-krb4 --without-ucdsnmp
> --with-bdb-incdir=/usr/local/BerkeleyDB.4.0/include
> --with-bdb-libdir=/usr/local/BerkeleyDB.4.0/lib --with-dblib=berkeley
> --with-dbpath=/usr/local/BerkeleyDB.4.0 --with-lock=fcntl
> --with-mboxlist-db=skiplist --with-seen-db=skiplist  --without-notify
> --disable-sieve --enable-fulldirhash --with-idle=no
> --with-duplicate-db=skiplist
>
> I run "strace -T -p pid", in which pid is pid of lmtpd. The following line
> catches my eyes.
>
> writev(11, [{"\0\0\0018(\"Sat, 7 Sep 2002 22:12:14 -"..., 316},
> {"\0\0\0Q(\"TEXT\" \"PLAIN\" (\"CHARSET\" {"..., 88}, {"\0\0\0E(\"TEXT\"
> \"PLAIN\" (\"CHARSET\" {"..., 76},
> {"\0\0\0000\0\0\0\2\0\0\0\0\0\0\2Y\0\0\2Y\0\0\0000\377\377"..., 52},
> {"\0\0\0\0", 4}, {"\0\0\0*loadtest <loadtest1586 at web9."..., 48},
> {"\0\0\0!<loadtest1586 at web9.swlab.rim"..., 40}, {"\0\0\0\0", 4},
> {"\0\0\0\0", 4}, {"\0\0\0\3NIL\0", 8}], 10) = 640 <1.207524>
>
> It takes 1.2 sec to do writev() for each email! I search through the code
in
> /imap/messages.c. It looks like the following function is doing the
writing:
>
> /*
>  * Write the BODY (if 'newformat' is zero) or BODYSTRUCTURE
>  * (if 'newformat' is nonzero) for 'body' to 'ibuf'.
>  */
> static void
> message_write_body(ibuf, body, newformat)
>
> I wonder why writev() takes so long to do the writing? In the mean time I
> don't found error messages about locking. I guess it is not
> "duplicate_check" who is take so long. It there any thing to don with my
> configurations, or sendmail's configuration?
>
> Thanks a lot.
>
>
> Su
>
> Research In Motion
> (519)888-7465 ext 3041