Re: dt: make vmm tracepoints amd64 only
On Mon, Jan 17, 2022 at 04:51:37PM -0800, Philip Guenther wrote: > On Mon, Jan 17, 2022 at 5:02 AM Klemens Nanni wrote: > > > These don't hurt on !VMM architectures but I was still surprised to see > > them on e.g. sparc64: > > > > # arch -s ; btrace -l | grep vmm > > sparc64 > > tracepoint:vmm:guest_enter > > tracepoint:vmm:guest_exit > > > > Like some network drivers, we could use __amd64__ to limit those to > > amd64 and save a few bits in all other kernels. > > > > Is this approach feasible or should we just ignore such one-offs? > > > > If there's a non-trivial number of trace points in drivers, then it would > suggest that such tracepoints should be added/registered/pick-a-term by the > driver's attach routine. This needs a little bit of refactor around probe registration. I plan to commit the initial `#ifdef __amd64__' diff with "OK pv" soon unless I hear objections.
Re: dt: make vmm tracepoints amd64 only
On Mon, Jan 17, 2022 at 5:02 AM Klemens Nanni wrote: > These don't hurt on !VMM architectures but I was still surprised to see > them on e.g. sparc64: > > # arch -s ; btrace -l | grep vmm > sparc64 > tracepoint:vmm:guest_enter > tracepoint:vmm:guest_exit > > Like some network drivers, we could use __amd64__ to limit those to > amd64 and save a few bits in all other kernels. > > Is this approach feasible or should we just ignore such one-offs? > If there's a non-trivial number of trace points in drivers, then it would suggest that such tracepoints should be added/registered/pick-a-term by the driver's attach routine. Philip
Re: dt: make vmm tracepoints amd64 only
On Mon, Jan 17, 2022 at 10:10:26AM -0300, Crystal Kolipe wrote: > On Mon, Jan 17, 2022 at 01:00:44PM +, Klemens Nanni wrote: > > These don't hurt on !VMM architectures but I was still surprised to see > > them on e.g. sparc64: > > > > # arch -s ; btrace -l | grep vmm > > sparc64 > > tracepoint:vmm:guest_enter > > tracepoint:vmm:guest_exit > > > > Like some network drivers, we could use __amd64__ to limit those to > > amd64 and save a few bits in all other kernels. > > Don't we want this on i386 too? > pd@ removed i386 vmm(4) years ago. It was sorta pointless running VMs on a host that can only support 4GB physmem.
Re: dt: make vmm tracepoints amd64 only
On Mon, Jan 17, 2022 at 08:34:39AM -0500, Dave Voutila wrote: > vmm(4) was removed from i386 hosts a couple years ago if my memory is > correct. Ah, my bad. It was indeed removed on 20190118.
Re: dt: make vmm tracepoints amd64 only
Crystal Kolipe writes: > On Mon, Jan 17, 2022 at 01:00:44PM +, Klemens Nanni wrote: >> These don't hurt on !VMM architectures but I was still surprised to see >> them on e.g. sparc64: >> >> # arch -s ; btrace -l | grep vmm >> sparc64 >> tracepoint:vmm:guest_enter >> tracepoint:vmm:guest_exit >> >> Like some network drivers, we could use __amd64__ to limit those to >> amd64 and save a few bits in all other kernels. I'm ok with this. bt(5) scripts don't reference tracepoints by anything other than name, so there's no point in having them on unsupported platforms. > > Don't we want this on i386 too? vmm(4) was removed from i386 hosts a couple years ago if my memory is correct. -dv
Re: dt: make vmm tracepoints amd64 only
On 2022/01/17 10:10, Crystal Kolipe wrote: > On Mon, Jan 17, 2022 at 01:00:44PM +, Klemens Nanni wrote: > > These don't hurt on !VMM architectures but I was still surprised to see > > them on e.g. sparc64: > > > > # arch -s ; btrace -l | grep vmm > > sparc64 > > tracepoint:vmm:guest_enter > > tracepoint:vmm:guest_exit > > > > Like some network drivers, we could use __amd64__ to limit those to > > amd64 and save a few bits in all other kernels. > > Don't we want this on i386 too? vmm is amd64 only.
Re: dt: make vmm tracepoints amd64 only
On Mon, Jan 17, 2022 at 01:00:44PM +, Klemens Nanni wrote: > These don't hurt on !VMM architectures but I was still surprised to see > them on e.g. sparc64: > > # arch -s ; btrace -l | grep vmm > sparc64 > tracepoint:vmm:guest_enter > tracepoint:vmm:guest_exit > > Like some network drivers, we could use __amd64__ to limit those to > amd64 and save a few bits in all other kernels. Don't we want this on i386 too?
dt: make vmm tracepoints amd64 only
These don't hurt on !VMM architectures but I was still surprised to see
them on e.g. sparc64:
# arch -s ; btrace -l | grep vmm
sparc64
tracepoint:vmm:guest_enter
tracepoint:vmm:guest_exit
Like some network drivers, we could use __amd64__ to limit those to
amd64 and save a few bits in all other kernels.
Is this approach feasible or should we just ignore such one-offs?
One can specify and "use" those tracepoints without errors in btrace(8),
but they won't ever hit on !amd64, of course.
Tested on amd64 and sparc64.
Index: dev/dt//dt_prov_static.c
===
RCS file: /cvs/src/sys/dev/dt/dt_prov_static.c,v
retrieving revision 1.11
diff -u -p -r1.11 dt_prov_static.c
--- dev/dt//dt_prov_static.c24 Nov 2021 09:47:49 - 1.11
+++ dev/dt//dt_prov_static.c17 Jan 2022 12:47:38 -
@@ -69,11 +69,13 @@ DT_STATIC_PROBE3(vfs, bufcache_rel, "lon
DT_STATIC_PROBE3(vfs, bufcache_take, "long", "int", "int64_t");
DT_STATIC_PROBE4(vfs, cleaner, "long", "int", "long", "long");
+#ifdef __amd64__
/*
* VMM
*/
DT_STATIC_PROBE2(vmm, guest_enter, "void *", "void *");
DT_STATIC_PROBE3(vmm, guest_exit, "void *", "void *", "uint64_t");
+#endif /* __amd64__ */
/*
* SMR
@@ -113,9 +115,11 @@ struct dt_probe *dtps_static[] = {
&_DT_STATIC_P(vfs, bufcache_rel),
&_DT_STATIC_P(vfs, bufcache_take),
&_DT_STATIC_P(vfs, cleaner),
+#ifdef __amd64__
/* VMM */
&_DT_STATIC_P(vmm, guest_enter),
&_DT_STATIC_P(vmm, guest_exit),
+#endif /* __amd64__ */
/* SMR */
&_DT_STATIC_P(smr, call),
&_DT_STATIC_P(smr, called),
