Messages in this thread | | | Subject | Re: [PATCH v2 17/23] x86/resctrl: Abstract __rmid_read() | From | Reinette Chatre <> | Date | Wed, 20 Oct 2021 11:15:28 -0700 |
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Hi Babu,
On 10/19/2021 4:20 PM, Babu Moger wrote: > Hi James, > > On 10/1/21 11:02 AM, James Morse wrote: >> __rmid_read() selects the specified eventid and returns the counter >> value from the msr. The error handling is architecture specific, and >> handled by the callers, rdtgroup_mondata_show() and __mon_event_count(). >> >> Error handling should be handled by architecture specific code, as >> a different architecture may have different requirements. MPAM's >> counters can report that they are 'not ready', requiring a second >> read after a short delay. This should be hidden from resctrl. >> >> Make __rmid_read() the architecture specific function for reading >> a counter. Rename it resctrl_arch_rmid_read() and move the error >> handling into it. >> >> Signed-off-by: James Morse <james.morse@arm.com> >> --- >> Changes since v1: >> * Return EINVAL from the impossible case in __mon_event_count() instead >> of an x86 hardware specific value. >> --- >> arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 4 +-- >> arch/x86/kernel/cpu/resctrl/internal.h | 2 +- >> arch/x86/kernel/cpu/resctrl/monitor.c | 42 +++++++++++++++-------- >> include/linux/resctrl.h | 1 + >> 4 files changed, 31 insertions(+), 18 deletions(-) >> >> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c >> index 25baacd331e0..c8ca7184c6d9 100644 >> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c >> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c >> @@ -579,9 +579,9 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg) >> >> mon_event_read(&rr, r, d, rdtgrp, evtid, false); >> >> - if (rr.val & RMID_VAL_ERROR) >> + if (rr.err == -EIO) >> seq_puts(m, "Error\n"); >> - else if (rr.val & RMID_VAL_UNAVAIL) >> + else if (rr.err == -EINVAL) >> seq_puts(m, "Unavailable\n"); >> else >> seq_printf(m, "%llu\n", rr.val * hw_res->mon_scale); > > This patch breaks the earlier fix > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=064855a69003c24bd6b473b367d364e418c57625 > > When the user reads the events on the default monitoring group with > multiple subgroups, the events on all subgroups are consolidated > together. In case if the last rmid read was resulted in error then whole > group will be reported as error. The err field needs to be cleared. > > Please add this patch to clear the error. > > diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c > b/arch/x86/kernel/cpu/resctrl/monitor.c > index 14bc843043da..0e4addf237ec 100644 > --- a/arch/x86/kernel/cpu/resctrl/monitor.c > +++ b/arch/x86/kernel/cpu/resctrl/monitor.c > @@ -444,6 +444,8 @@ void mon_event_count(void *info) > /* Report error if none of rmid_reads are successful */ > if (ret_val) > rr->val = ret_val; > + else > + rr->err = 0; > } > > /* >
Good catch, thank you.
Even so, I do not think mon_event_count()'s usage of __mon_event_count() was taken into account by this patch and needs a bigger rework than the above fixup. For example, if I understand correctly ret_val is the error and rr->val no longer expected to contain the error after this patch. So keeping that assignment to rr->val is not correct.
Reinette
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