Date: Thu, 15 Jul 1999 11:25:39 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Noriyuki Soda <soda@sra.co.jp> Cc: freebsd-hackers@FreeBSD.ORG, tech-userlevel@netbsd.org Subject: Re: Swap overcommit (was Re: Replacement for grep(1) (part 2)) Message-ID: <199907151825.LAA11948@apollo.backplane.com> References: <378D67B3.3E2A703C@newsguy.com> <Pine.GSO.3.95.990715082122.11860B-100000@jericho> <199907151738.CAA10933@srapc342.sra.co.jp> <199907151809.LAA11823@apollo.backplane.com> <199907151819.DAA11342@srapc342.sra.co.jp>
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:: -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.
-Matt
Matthew Dillon
<dillon@backplane.com>
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