On Thursday 03 March 2005 07:35 am, David Schultz wrote:
On Thu, Mar 03, 2005, John Baldwin wrote:
Hence, don't kill this whole feature just because someone is too
lazy to fix a bug.
Fair enough. I'll defer to you on the extent of the problem.
David seemed to think that it was more widespread. (BTW, does
*anyone* know what the PHOLD() in kern_physio is for? Is it a
holdover from when the PCB was in struct user?)
I've wondered about this myself in the past. I went looking once and
discovered that it never did anything that I could find. I believe it
is a case of 'because it was always done that way' or because the
pseudocode in the Bach or bsd books had it. There is certainly no
functional need for it in FreeBSD.
kern_physio prevents chunks of memory needed for IO from being paged
out. Swapping out a thread in kern_physio will prevent it from releasing
the resources soon. With minphys > stack size I think PHOLD() is still a