December 2002
Intermediate to advanced
1232 pages
56h 38m
English
Content preview from Sendmail, 3rd EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
Tune the Kernel
Device I/O under Unix is handled by the kernel. The default device settings for most kernels provide somewhat equal performance for a wide range of possible applications. But no kernel, supplied off the shelf, is tuned for best TCP/IP and email performance.
In this section we outline considerations for tuning your kernel. Unfortunately, we cannot give specific tuning instructions because tuning is as widely varied as the varieties and versions of Unix itself. Some versions of Unix, for example, are tuned by running special programs, others are tuned by editing boot-time files, and yet others are tuned by editing source files and compiling a new kernel.
In general, the tuning items of highest concern for best email performance are:
Maximize file descriptor limits.
Disable source-routed packets.
Maximize the number of simultaneous possible TCP/IP connections.
Maximize TCP/IP buffer sizes.
Decrease TCP/IP keepalive intervals.
Other items of concern are, for example, disk I/O, the number of inodes supported on a disk, the bandwidth of your Internet connection, and the throughput guaranteed by your ISP. As we said at the beginning of this chapter, the topic of performance tuning in sendmail is so complex that it deserves a book of its own.
In the discussions that follow, first change kernel settings by hand to make sure nothing breaks. Only when proven, add those settings to boot-time scripts and document what you did.
Maximize File Descriptor Limits
A file descriptor is the ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.