Date: Sun, 7 Dec 2003 14:49:25 -0800 (PST) From: Alan Cox <alc@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/i386/i386 vm_machdep.c src/sys/i386/include sf_buf.h Message-ID: <200312072249.hB7MnPKe007408@repoman.freebsd.org>
next in thread | raw e-mail | index | archive | help
alc 2003/12/07 14:49:25 PST
FreeBSD src repository
Modified files:
sys/i386/i386 vm_machdep.c
sys/i386/include sf_buf.h
Log:
Don't remove the virtual-to-physical mapping when an sf_buf is freed.
Instead, allow the mapping to persist, but add the sf_buf to a free list.
If a later sendfile(2) or zero-copy send resends the same physical page,
perhaps with the same or different contents, then the mapping overhead is
avoided and the sf_buf is simply removed from the free list.
In other words, the i386 sf_buf implementation now behaves as a cache of
virtual-to-physical translations using an LRU replacement policy on
inactive sf_bufs. This is similar in concept to a part of
http://www.cs.princeton.edu/~yruan/debox/ patch, but much simpler in
implementation. Note: none of this is required on alpha, amd64, or ia64.
They now use their direct virtual-to-physical mapping to avoid any
emphemeral mapping overheads in their sf_buf implementations.
Revision Changes Path
1.220 +10 -9 src/sys/i386/i386/vm_machdep.c
1.3 +1 -0 src/sys/i386/include/sf_buf.h
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200312072249.hB7MnPKe007408>