Date: Thu, 15 Jul 1999 17:44:25 -0500 (CDT) From: Jonathan Lemon <jlemon@americantv.com> To: hackers@freebsd.org Subject: Re: Swap overcommit (was Re: Replacement for grep(1) (part 2)) Message-ID: <199907152244.RAA12439@free.pcs> In-Reply-To: <local.mail.freebsd-hackers/199907151825.LAA11948@apollo.backplane.com> References: <local.mail.freebsd-hackers/378D67B3.3E2A703C@newsguy.com> <local.mail.freebsd-hackers/Pine.GSO.3.95.990715082122.11860B-100000@jericho> <local.mail.freebsd-hackers/199907151738.CAA10933@srapc342.sra.co.jp> <local.mail.freebsd-hackers/199907151809.LAA11823@apollo.backplane.com> <local.mail.freebsd-hackers/199907151819.DAA11342@srapc342.sra.co.jp>
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In article <local.mail.freebsd-hackers/199907151825.LAA11948@apollo.backplane.com> you write: >:: -s Print summary information about total swap >:: space usage and availability: >:: >:: allocated The total amount of swap space >:: (in 1024-byte blocks) >:: currently allocated for use as >:: backing store. >:: >:: reserved The total amount of swap space >:: (in 1024-bytes blocks) not >:: currently allocated, but >:: claimed by memory mappings for >:: possible future use. >:: >:: used The total amount of swap space >:: (in 1024-byte blocks) that is >:: either allocated or reserved. >:-- >:soda > > It would be really easy to test this. > > Write a program that malloc's 32MB of space and touches it, > then sleeps 10 seconds and forks, with both child and parent > sleeping afterwords. ( the parent and the forked child should > not touch the memory after the fork occurs ). > > Do a pstat -s before, after the initial touch, and after > the fork. If you do not see the reserved swap space jump > by 32MB after the fork, it isn't what you thought it was. aladdin[5:32pm]> prtconf System Configuration: Sun Microsystems i86pc Memory size: 128 Megabytes aladdin[5:41pm]> uname -a SunOS aladdin 5.6 Generic_105182-14 i86pc i386 total: 67280k bytes allocated + 28668k reserved = 95948k used, 196460k avail malloced 32MB... total: 67320k bytes allocated + 61460k reserved = 128780k used, 163592k avail touched... total: 100084k bytes allocated + 28696k reserved = 128780k used, 163732k avail forking... total: 100092k bytes allocated + 61520k reserved = 161612k used, 130864k avail touching again (parent)... touching again (child)... total: 132864k bytes allocated + 28748k reserved = 161612k used, 130760k avail exiting... exiting... total: 67248k bytes allocated + 28700k reserved = 95948k used, 196448k avail -- Jonathan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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