Date: Tue, 9 Jul 2002 02:46:17 -0700 From: David Schultz <dschultz@uclink.berkeley.edu> To: Terry Lambert <tlambert2@mindspring.com> Cc: "Brandon D. Valentine" <bandix@geekpunk.net>, Matthew Dillon <dillon@apollo.backplane.com>, Erik Trulsson <ertr1013@student.uu.se>, Chuck Robey <chuckr@chuckr.org>, FreeBSD Hackers List <freebsd-hackers@FreeBSD.ORG> Subject: Re: swap & huge mem systems Message-ID: <20020709094617.GA28249@HAL9000.wox.org> In-Reply-To: <3D2A9BC8.D4CB1087@mindspring.com> References: <20020709023121.X11678-100000@dallben.homeportal.2wire.net> <3D2A9BC8.D4CB1087@mindspring.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Thus spake Terry Lambert <tlambert2@mindspring.com>: > "Brandon D. Valentine" wrote: > > Allocating swap = physical RAM doesn't buy you any expansion though. I > > always try to do at least twice physical RAM so that if I ever double > > the RAM in my machine I'm still able to catch crash dumps. It's not > > worth having to repartition the drive to add more swap every time I add > > more RAM when a 120GB 7.2k drive is ~$170. What's 2GB of swap on a > > 120GB disk or even a 40GB disk for that matter? The way you said that makes it sound like you're always doubling the RAM of your machines, but you never have more than one disk. When you expand your RAM, you can always buy another one of those dirt cheap hard drives you mention (which will of course cost half as much per gigabyte as the old one did). If you care to reclaim the `precious' space consumed by the swap partition on the old drive, just merge it with /tmp, or whatever partition it happens to be next to. Alternatively, you can increase swap throughput by using both disks for swap, even though it's sub-optimal to have different-sized swap partitions. > 2G of swap on a 40G disk is 5%. > > This is the same amount that people are unwilling to "give up" > for the free reserve in order to permit the FFS block allocation > algorithm to go from a 95% fill rate to a 90% fill rate, upping > the effective efficiency by a factor of ~8. > > "Sure, it's more efficient for the *computer*, but I buy disk space > for *me*; if the *computer* want's more disk space, it can get a job > and buy its own damn disk space!". The free reserve is an issue of efficiency, not expansion. I'd like to think that most people keep at least 10% free on their filesystems for the sake of reduced fragmentation. If doubling swap space increased efficiency, I'm sure everyone would put their extra disk space into that instead. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20020709094617.GA28249>