Gentoo Archives: gentoo-amd64

From: Richard Freeman <rich0@×××××××.net>
To: gentoo-amd64@l.g.o
Subject: Re: [gentoo-amd64] Re: 64-bit or 32-bit?
Date: Tue, 12 Jul 2005 20:21:54
Message-Id: 49847.155.91.6.71.1121199590.squirrel@rich.homedns.org
In Reply to: Re: [gentoo-amd64] Re: 64-bit or 32-bit? by Kyle Liddell
1 On Tue, July 12, 2005 1:51 pm, Kyle Liddell said:
2 > but will help when you realize "oh no, I need another 500mb
3 > for /var/tmp/portage"...
4 >
5
6 On my system I have /tmp and /var/tmp mounted as tmpfs. My philosophy is
7 that nothing important should be in there anyway, and if I'm buliding I
8 really don't care whether the files being compiled are ever committed to
9 disk. The advantage of tmpfs is that if there is no need to free up RAM,
10 your build directory will never get written to disk at all - just the
11 final merged files. Of course, you'll need a few GB of RAM/swap to
12 accomplish this, and when doing the rare openoffice-scale build I usually
13 need to resize the tmpfs or run off of disk.
14
15 If you're swapping you might wonder what the advantage of using tmpfs over
16 a regular filesystem is. After all, it is getting written to disk either
17 way, right? Well, if you write to a regular filesystem the system will
18 hold the data in buffers/cache for no more than a few seconds - to
19 minimize the amount of data lost if power fails. After all, if you write
20 to a filesystem you expect the data to be around after a reboot. On the
21 other hand, with tmpfs the memory gets swapped like anything else based on
22 frequency of use and all that. There is no long-term concern for
23 fragmented disk space, and a frequently accessed file will never get
24 swapped at all. At the end of the emerge, the work directory is deleted
25 and rather than a mad rush to update inodes the memory is simply
26 unallocated (which requires no disk access).
27
28 Some day I should time a build using tmpfs vs a regular filesystem and see
29 how large the difference is. Obviously it will be more pronounced for
30 those with more RAM - although even Duncan might have to resort to turning
31 on swap to actually take advantage of it.
32 --
33 gentoo-amd64@g.o mailing list