Add /dev/zero mention for anon mmap().

diff --git a/doc/TODO.detail/mmap b/doc/TODO.detail/mmap
index 1ea7b85d027dc2ac13b6436947ad77a391f46e3f..77dc3993afb226c6aab3115ba22e08f9000298e4 100644 (file)
--- a/doc/TODO.detail/mmap
+++ b/doc/TODO.detail/mmap
@@ -482,3 +482,96 @@ TIP 6: Have you searched our list archives?
 
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+From [email protected] Mon Jun  3 17:54:43 2002
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+   Mon, 3 Jun 2002 16:52:57 -0500 (CDT)\r
+Message-ID: <[email protected]>\r
+From: "Igor Kovalenko" \r
+To: "Bruce Momjian" \r
+cc: "Tom Lane" , "mlw" ,\r
+   "Marc G. Fournier" , \r
+References: <[email protected]>\r
+Subject: Re: [HACKERS] HEADS UP: Win32/OS2/BeOS native ports\r
+Date: Mon, 3 Jun 2002 16:53:51 -0500\r
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+That's what Apache does. Note, on most platforms MAP_ANON is equivalent to
+mmmap-ing /dev/zero. Solaris for example does not provide MAP_ANON but using
+
+fd=open(/dev/zero)
+mmap(fd, ...)
+close(fd)
+
+works just fine.
+
+----- Original Message -----
+From: "Bruce Momjian" 
+To: "Igor Kovalenko" 
+Cc: "Tom Lane" ; "mlw" ; "Marc G.
+Fournier" ; 
+Sent: Sunday, June 02, 2002 7:47 PM
+Subject: Re: [HACKERS] HEADS UP: Win32/OS2/BeOS native ports
+
+
+> Igor Kovalenko wrote:
+> > It does not have to be anonymous. POSIX also defines shm_open(same
+arguments
+> > as open) API which will create named object in whatever location
+corresponds
+> > to shared memory storage on that platform (object is then grown to
+needed
+> > size by ftruncate() and the fd is then passed to mmap). The object will
+> > exist in name space and can be detected by subsequent calls to
+shm_open()
+> > with same name. It is not really different from doing open(), but more
+> > portable (mmap() on regular files may not be supported).
+>
+> Actually, I think the best shared memory implemention would be
+> MAP_ANON | MAP_SHARED mmap(), which could be called from the postmaster
+> and passed to child processes.
+>
+> While all our platforms have mmap(), many don't have MAP_ANON, but those
+> that do could use it.  You need MAP_ANON to prevent the shared memory
+> from being written to a disk file.
+>
+> --
+>   Bruce Momjian                        |  http://candle.pha.pa.us
+>   [email protected]               |  (610) 853-3000
+>   +  If your life is a hard drive,     |  830 Blythe Avenue
+>   +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026
+>
+
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