Date: Wed, 06 Dec 2000 17:23:30 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: remy@boostworks.com Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: free() not freing pagedirs pages. Message-ID: <51350.976119810@critter> In-Reply-To: Your message of "Wed, 06 Dec 2000 17:11:53 %2B0100." <200012061612.RAA30340@luxren2.boostworks.com>
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In message <200012061612.RAA30340@luxren2.boostworks.com>, Remy Nonnenmacher wr ites: >>From the /usr/src/lib/libc/stdlib/malloc.c sources, it seems that this >is due to not shrinking/relocating pagedir pages (free_pages(), comment >around line 940). This means that returning pages stop at first >allocated pagedir. That is actually not correct. the pagedir is allocated with mmap from anonymous memory and does not affect the sbrk(2)'ing. >It seems to be a problem also in some other Unixes, anyway, but i would >like to know if: Presuming your question then is "can the pagedir be shrunk ?" the answers are: >1) This is historical and must not be fixed. no. >2) This can be easily fixed. maybe. >3) Fixing it would lead to enormous problems. Better keep it like this. unlikely. Have you read the paper in src/share/doc/papers/malloc ? Also, if you are truly concerned with the returning to the OS of memory, examine the 'H' option to phkmalloc. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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