Re: [patch] linux 2.4.17: The second mb() rework (final)

On Fri, 15 Feb 2002, Atsushi Nemoto wrote:

Note that SYNC on TX39/H and TX39/H2 does not flush a write buffer.

 That's perfectly fine -- it does not need to.  It's only a
synchronization point.

Some operation (for example, bc0f loop) are required to flush a write
buffer.

 This is bad, though.  No extra operations must be needed.  After a "sync" 
the buffer should be written back as soon as not doing so would be visible
externally.  IOW, two consecutive writes separated by a "sync" need not
imply a write-back, but as soon as a read happens a preceding write-back
is a must.

 It sounds weird: it looks like "sync" is useless and basically a "nop". 
If this is the case the processors need their own wbflush()
implementation.  Can you point to specific chapters of specifications that
document it?

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +