Date: Wed, 28 Feb 2001 16:18:37 +0900 From: "Akinori MUSHA" <knu@iDaemons.org> To: Matt Dillon <dillon@FreeBSD.org>, sanpei@FreeBSD.org Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/i386/linux linux_machdep.c Message-ID: <86u25fxoky.wl@archon.local.idaemons.org> In-Reply-To: <200102280430.f1S4UST14589@freefall.freebsd.org> References: <200102280430.f1S4UST14589@freefall.freebsd.org>
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At Tue, 27 Feb 2001 20:30:28 -0800 (PST),
dillon wrote:
> dillon 2001/02/27 20:30:28 PST
>
> Modified files:
> sys/i386/linux linux_machdep.c
> Log:
> Linux does not filesystem-sync file-backed writable mmap pages on
> a regular basis. Adjust our linux emulation to conform. This will
> cause more dirty pages to be left for the pagedaemon to deal with,
> but our new low-memory handling code can deal with it. The linux
> way appears to be a trend, and we may very well make MAP_NOSYNC the
> default for FreeBSD as well (once we have reasonable sequential
> write-behind heuristics for random faults).
> (will be MFC'd prior to 4.3 freeze)
>
> Suggested by: Andrew Gallatin
How does it compare to the attached patch which came up in the
FreeBSD-users-jp mailing list in Japan some time ago?
It gives users an option to switch the behavior via sysctl(8), and
does <<bsd_args.flags |= MAP_NOSYNC;>> in a different place.
The patch was originally posted by sanpei@FreeBSD.org, and is
mentioned in Hints.FreeBSD of the vmware2 port, FYI.
--
/
/__ __ Akinori.org / MUSHA.org
/ ) ) ) ) / FreeBSD.org / Ruby-lang.org
Akinori MUSHA aka / (_ / ( (__( @ iDaemons.org / and.or.jp
"We're only at home when we're on the run, on the wing, on the fly"
--- sys/i386/linux/linux_machdep.c 2001/02/16 16:40:43 1.12
+++ sys/i386/linux/linux_machdep.c 2001/02/27 15:37:29
@@ -31,6 +31,7 @@
#include <sys/param.h>
#include <sys/mman.h>
#include <sys/proc.h>
+#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/systm.h>
#include <sys/unistd.h>
@@ -288,6 +289,11 @@
int pos;
};
+static int mmap_nosync;
+SYSCTL_DECL(_compat_linux);
+SYSCTL_INT(_compat_linux, OID_AUTO, mmap_nosync, CTLFLAG_RW,
+ &mmap_nosync, 0, "mmap files with MAP_NOSYNC flag in Linux mode.");
+
#define STACK_SIZE (2 * 1024 * 1024)
#define GUARD_SIZE (4 * PAGE_SIZE)
@@ -395,8 +401,11 @@
bsd_args.prot = linux_args.prot | PROT_READ; /* always required */
if (linux_args.flags & LINUX_MAP_ANON)
bsd_args.fd = -1;
- else
+ else {
bsd_args.fd = linux_args.fd;
+ if (mmap_nosync)
+ bsd_args.flags |= MAP_NOSYNC;
+ }
bsd_args.pos = linux_args.pos;
bsd_args.pad = 0;
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