Date: Wed, 22 Dec 1999 22:48:03 +0100 From: Guido van Rooij <guido@gvr.org> To: Peter Wemm <peter@netplex.com.au> Cc: Hidetoshi Shimokawa <simokawa@sat.t.u-tokyo.ac.jp>, vsilyaev@mindspring.com, dillon@freebsd.org, freebsd-emulation@FreeBSD.ORG, dbutter@wireless.net Subject: Re: VMware: Questions... Message-ID: <19991222224803.A410@gvr.gvr.org> In-Reply-To: <19991220153149.AD13C1CCE@overcee.netplex.com.au>; from Peter Wemm on Mon, Dec 20, 1999 at 11:31:49PM %2B0800 References: <simokawa@sat.t.u-tokyo.ac.jp> <19991220153149.AD13C1CCE@overcee.netplex.com.au>
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On Mon, Dec 20, 1999 at 11:31:49PM +0800, Peter Wemm wrote: > > > > This is because mmaped file is written every 30 second by sync daemon. > > The file is usually named /var/tmp/ram0 but it's unlinked right after > > opened so you cannot see it by 'ls' although it exits. > > It would be nice if the VFS/VM system detected this automatically and > switched on NOSYNC for files that got unlinked... I wouldn't be suprised if > this is what Linux does. Matt, is this possible? > I havent seen an answer to this question yet. If it is possible, that would be very nice. I doubt it though, but my knowledge on that part of the system is rather limited. A quick workaround could be to look at the ref count of the underlying inode of the fd passed to the linux mmap If the refcount is one then clearly the inode is no being referenced through a directory entry in the file system. This could even be done for the general mmap call (provided a regular file of course). But it might be a very specific situation because one usually would not used a file backed mmap in FreeBSD, yet use an anonymous mmap. -Guido To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-emulation" in the body of the message
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