Re: Need help with phys backed shm segments (Postgresql+FreeBSD).

* Alfred Perlstein <bright(at)wintelcom(dot)net> [001205 12:30] wrote:
> * Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> [001205 08:37] wrote:
> > BTW, I just remembered that in 7.0.*, the SLocks that are managed by
> > SpinAcquire() all live in their own little shm segment. On a machine
> > where slock_t is char, it'd likely only amount to 128 bytes or so.
> > Maybe you are seeing some bug in FreeBSD's handling of tiny shm
> > segments?
>
> Good call, i think I found it! :)

Here's the patch I'm using on FreeBSD, it seems to work, if any
other FreeBSD'ers want to try it out, just apply the patch:
cd /usr/src/sys/vm ; patch < patchfile

and recompile and boot with a new kernel, then do this:

sysctl -w kern.ipc.shm_use_phys=1

or add:
kern.ipc.shm_use_phys=1
to /etc/sysctl.conf

Let me know if it works.

thanks,
-Alfred

Index: phys_pager.c
===================================================================
RCS file: /home/ncvs/src/sys/vm/phys_pager.c,v
retrieving revision 1.3.2.1
diff -u -u -r1.3.2.1 phys_pager.c
--- phys_pager.c 2000/08/04 22:31:11 1.3.2.1
+++ phys_pager.c 2000/12/05 20:13:25
@@ -83,7 +83,7 @@
* Allocate object and associate it with the pager.
*/
object = vm_object_allocate(OBJT_PHYS,
- OFF_TO_IDX(foff + size));
+ OFF_TO_IDX(foff + PAGE_MASK + size));
object->handle = handle;
TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
pager_object_list);