[lkml]   [1999]   [Jun]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Fw: FENRIS (nwfs) Source Code Now Available.

On Mon, 21 Jun 1999, Jeff Merkey wrote:

> > [...] Also, Windows NT has some pretty nifty stuff
> > in it's file system architecture for SMP. The way the VM Cache manager is
> > implemented in Windows NT is nothing short of genius. By caching MCB
> > allocation run information (NT reads and writes files by constructing MCB
> > lists in memory, which are in-memory descriptors of a file's contiguous
> > sector runs), this gives NT the ability to perform some fairly
> > sophisticated read-ahead and cache predication operations for random
> > access as well as sequential access files. This architecture is also
> > superior for SMP operations. MCB lists can basically be sent in a
> > parallel fashion to the IO subsystem and transacted in parallel. [...]

would you mind comparing it to what Linux 2.3.7's page cache does? That
one has pagecache design pretty close to 'genius' as well, and not only on
paper :) On a 4-ways Xeon we scale read performance ~380%, which is
basically linear:

single-process reads done on the same 60k file:

[root@moon fileben]# ./fileben ./FILE 60000 1 1 1
READ: 273.76 MB/sec

4-process read()s done on the same 60k file:

[root@moon fileben]# ./fileben ./FILE 60000 4 1 1
READ: 258.16 MB/sec
READ: 258.09 MB/sec
READ: 258.04 MB/sec
READ: 258.20 MB/sec

part of the rather dramatic speedup is also a new mechanizm: the new
pagecache now also caches 'filesystem physical block addresses', which
allows us to skip a costy lookup of filesystem metadata for every block of
file read() or written.

-- mingo

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:52    [W:0.060 / U:6.056 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site