Date: Sun, 13 Jan 2002 12:42:59 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Alfred Perlstein <bright@mu.org> Cc: smp@freebsd.org, jhb@freebsd.org, dillon@freebsd.org Subject: Re: making malloc(9) smp safe? Message-ID: <3C41F153.DCA0A4F3@mindspring.com> References: <20020113050836.Q7984@elvis.mu.org>
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Alfred Perlstein wrote: > Malloc has its own mutex, however when it needs to do page allocations > via kmem_malloc() it drops the mutex and calls it. > > kmem_malloc() needs giant. > > what do I do? > > Do I grab giant before calling malloc(9)? > Do I make malloc(9) aquire or recurse on giant automatically? > (basically grab giant around kmem_malloc() call in malloc(9)) > > ? The way Dynix does this (see UNIX Internals: The New Frontiers, Uresh Vahalia, Chapter 12 Kernel Memory Allocation, 12.9 A Hierarchical Allocator for Multiprocessors) is to seperate the memory into a global pool, and per CPU pools, with a seperate Coelesce-to-Page layer. Here are some nice papers: http://www.research.ibm.com/K42/full-hotos-01.ps http://citeseer.nj.nec.com/mckenney96selecting.html http://citeseer.nj.nec.com/54799.html http://citeseer.nj.nec.com/bonwick94slab.html http://citeseer.nj.nec.com/wilson95dynamic.html http://citeseer.nj.nec.com/gamsa99tornado.html Yyou can get a copy of the original paper: "Efficient Kernel Memory Allocation on Shared-Memory Multiprocessors" P.E. McKenney, J. Slingwine Processdings of Usenix, Winter, 1993 (p295-305). Paul's current email address is: pmckenne@us.ibm.com (he works in the Linux Technology Center at IBM Watson Research). You can get the mother of all papers on SMP kernel memory allocation from his home page at: http://www.rdrop.com/users/paulmck He has quite a nice set of papers on SMP, locking, and memory allocation. Here is another paper he's been involved with recently; it's also quite applicable to the problem at hand: http://lwn.net/2001/features/OLS/pdf/pdf/read-copy.pdf -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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