14 messages in org.freebsd.freebsd-archRemoving kernel thread stack swapping| From | Sent On | Attachments |
|---|---|---|
| David Schultz | Mar 3, 2005 7:42 am | |
| Ryan Sommers | Mar 3, 2005 2:12 pm | |
| David Xu | Mar 3, 2005 2:37 pm | |
| Scott Long | Mar 3, 2005 2:51 pm | |
| John Baldwin | Mar 3, 2005 2:52 pm | |
| David Schultz | Mar 3, 2005 3:35 pm | |
| M. Warner Losh | Mar 3, 2005 4:47 pm | |
| Stephan Uphoff | Mar 3, 2005 4:51 pm | |
| Brooks Davis | Mar 3, 2005 4:58 pm | |
| David Xu | Mar 3, 2005 11:29 pm | |
| Scott Long | Mar 4, 2005 12:34 am | |
| Christoph Hellwig | Mar 5, 2005 9:17 am | |
| Peter Wemm | Mar 15, 2005 5:43 pm | |
| Stephan Uphoff | Mar 15, 2005 7:19 pm |
| Subject: | Removing kernel thread stack swapping | |
|---|---|---|
| From: | Stephan Uphoff (up...@tree.com) | |
| Date: | Mar 15, 2005 7:19:49 pm | |
| List: | org.freebsd.freebsd-arch | |
On Tue, 2005-03-15 at 20:43, Peter Wemm wrote:
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 good idea.
Stephan