guy keren wrote: > > On Sun, 30 Jan 2000, Omer Efraim wrote: > > if you want to check on improving a situation, you first need to check > exactly what is the situation - i'm not suer that the current method, of > forking off a process for each connection, is very problematic - the life > time of the process is much larger then the ammount of time it takes to > fork it off (i.e. you often take a minute or a few minutes to download > email - the fork operation takes less then one 10th of a second - now, is > _this_ where you should optimize??). Don't forget that on large corporate mail systems quite a lot of the cpu load comes from people _checking_ for mail. Imagine 10k users, each checking for mail every 5 minutes. Each one of those requires a fork even if the user has no (new?) mail. > > it sounds to me like a better place for optimization is storing compressed > email messages - it'll take more CPU power when storing the email, but you > could set up a capabilities system in which the client will speicy if it > can handle compressed email or not, and if it can, the decompression can > be done on the client side. this compress could make download time > smaller, and thus allow the server to support more clients. ofcourse, > there's a need to check which part takes longer - downloading the letters, > or compressing and decompressing them.. also note that this compressiong > will save up on I/O operations needed to save/load the letters, so it > might be that the compression itself is usefull even if the letters are > still sent to the clients in a non-compressed format... measurements are > needed here.... Well, I agree - but this is a whole other symphony and requires much more work, and it works on a much larger scale. I myself download mail tunneled through ssh so it's compressed anyhow, but I guess it would be nice to have clients supporting it out of the box. > > > I'm thinking about a qmail specific scenario (as this is the > > MTA I'm most familier with), but I'm sure this applies to > > other MTAs as well. > > well, with qmail you got one advantage that you don't have with sendmail > (for instalce) - the usage of mail dirs. when you have all mail stored in > one large file, the pop server needs to copy this email folder back and > forth when servicing the client. when using mail directories - this > copying operation is not required (unless a letter is not downloaded, and > rather has its UIDL data updated - anyone can tell if in qmail the header > and the letter's contents are stored in a single file, or in two seperate > files?) Single file. The reasoning behind Maildirs was not really performance but rather robustness. -- /--------------- Omer Efraim, omere@tcmail.tau.ac.il ------------------\ [ Microsoft Vaccine 2000 is configuring your immune system. This may ] [ take a few minutes. If your body stops responding for a long time and ] [ there is no brain activity please die. Setup will continue after you ] [ are reborn. ] \-----------------------------------------------------------------------/ - Quoting Buzh, asr
S/MIME Cryptographic Signature