Date: Tue, 24 Dec 2002 15:12:45 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: "Aaron Wohl" <freebsd@soith.com> Cc: freebsd-stable@FreeBSD.ORG Subject: Re: MAXDSIZ and pthreads large ram etc Message-ID: <200212242312.gBONCjqD044717@apollo.backplane.com> References: <20021224215413.B597F17A32@www.fastmail.fm>
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A user process has a 3G address space. The kernel takes the rest.
On a 4G machine you cannot make the kernel any smaller without creating
serious resource problems elsewhere.
MAXDSIZ does not encompass all the memory a program uses. MAXDSIZ
and mmap()'d memory are orthogonal data spaces. The larger you
set MAXDSIZ, the less VM is available for mmap(). MAXDSIZ really only
represents the program's heap (space available to malloc()).
Thread stacks are allocated with mmap(), and shared libraries are mapped
using mmap(). It is highly likely that you are increasing MAXDSIZ to
the point where the threaded programs you are running are unable to map
their thread's stacks.
-Matt
Matthew Dillon
<dillon@backplane.com>
:Anyone using a lot of address space per process (over 768megabytes)?
:
:For a machine with 4 gigabytes of ram im trying to up the amount of data
:a process can address. If I increase MAXDSIZ at about 2048mbyte pthreads
:stops working. Creating threads starts to fail. 4096mb seems to wrap
:the limit 0 zero. The kernel builds and boots but anything (sh) you try
:to run quits out of memory.
:
:Im currently using:
:options MAXDSIZ="(768*1024*1024)"
:
:Anyone got more than that to work? mysql uses pthreads much above 768mb
:pthread create starts to fail. This is on an AMD or intel processor with
:4.7 stable latest stuff checked out.
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