Date: Fri, 19 Jul 1996 05:33:34 -0700 From: David Greenman <davidg@root.com> To: heo@cslsun10.sogang.ac.kr (Heo Sung Gwan) Cc: freebsd-hackers@freebsd.org Message-ID: <199607191233.FAA14124@root.com> In-Reply-To: Your message of "Fri, 19 Jul 1996 20:09:05 %2B0700." <9607191109.AA05289@cslsun10.sogang.ac.kr>
next in thread | previous in thread | raw e-mail | index | archive | help
>I plan to modify the buffer cache to support multimedia files which are >accessed sequentially and do not have no locality of reference. Why? Is there some performance problem that you're experiancing with FreeBSD in this application that you need to work around? With FreeBSD's advanced read-ahead clustering and merged VM/buffer cache, you should achieve excellent performance without any modifications. >I want to know something about FreeBSD buffer cache implementation. > > 1) Where can I get the document about it?. No document exists (yet). > 2) Which files in kernel src directory is concerned with it? Mostly vfs_bio.c, but other components involved in file I/O are spread out over another half dozen or so files. > 3) How can I enlarge the part for buffer cache in physical memory? FreeBSD already uses all available free memory for file caching. It's really not accurate to talk about the "buffer cache" in FreeBSD since buffers no longer form the basis for file caching. File data is cached in VM objects and buffers are only used temporarily to provide the glue to the filesystems. > 4) How can user process access the file in ufs filesystem through raw disk? You can't unless you write a user-mode UFS/FFS that does it's I/O through the raw device. I couldn't imagine why you'd want to do this, however. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199607191233.FAA14124>