David Malone wrote:
On Sat, Jan 08, 2005 at 01:21:14PM -0500, Charles Sprickman wrote:
Any idea what type of impact this patch would have on say, a large qmail server that's drowning in context-switches?
It will depend on how many processes you have running at any one moment and how often processes are created/destroyed. From the look of the graphs, you won't really be able to tell unless there are significantly more than 1000 processes running at any moment.
David.
This could be the case.
It's my understanding that Qmail spawns a new qmail-local process (specifically qmail-lspawn exec's it) for each locally delivered message. For any remote message qmail-rspawn forks a qmail-remote process. I don't believe these processes live longer than a single instance. Depending on how his mailboxes are setup this can even result in new processes being spawned. If you're running vpopmail qmail-local will pipe the message to vdelivermail. And if you're running anything like spamassassin from vpopmail (as opposed to from qmail via the QMAIL_QUEUE patch, although that will spawn a spamc of it's own) this could result in another executed process (spamc is spamd's light-weight front-end).
Depending on how large and busy this qmail server is, there could definately be a large amount of time spent in process creation and teardown.
I'm not sure how much Charles is familiar with the Qmail+vpopmail+spamassassin, if he is using spamassassin. But, one of the "hidden" features of using SpamAssassin and Vpopmail as installed from ports is that spamassassin is called from vpopmail. There is no run-time option (only compile time that is defaulted to on) to disable this. A lot of users don't realize this and will use the QMAIL_QUEUE patch and run spamassassin from it. This can result in scanning every email twice, which can be a costly oversight.
-- Ryan Sommers [EMAIL PROTECTED]
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