Date: Mon, 24 Jun 2002 19:56:01 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: Alfred Perlstein <bright@mu.org> Cc: Patrick Thomas <root@utility.clubscholarship.com>, freebsd-hackers@freebsd.org Subject: Re: tunings for many httpds... Message-ID: <3D17DBC1.351A8A35@mindspring.com> References: <20020624151650.I68572-100000@utility.clubscholarship.com> <3D17D27A.11E82B2B@mindspring.com> <20020625022238.GH53232@elvis.mu.org>
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Alfred Perlstein wrote: > * Terry Lambert <tlambert2@mindspring.com> [020624 19:17] wrote: > > > > System V shared memory is allocated out of KVA space (annoying, > > but true). > > You keep saying this but the backing object allocated for sysvshm > is taken from either an OBJT_PHYS or OBJT_SWAP object. Uh, it's only ever an OBJT_SWAP; see line 532 of kern/sysv_shm.c. > At what point does it eat KVA that is other than for the backing > data structures? It eats address space, not RAM. And even if the mappings are not active (which they usually are, because of LRU and processes accessing them shared), the pages containing the page table entries for each process are themselves not swappable; anything with a large VSZ is going to eat 1/4k pages in KVA there, too. Ask yourself where a shared memory segment lives when it's not in attached to one process address space, prior to you ipcrm'ing it. It has to remain referenced so it isn't reclaimed. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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