Re: [PATCH] perf/x86/intel/uncore: Fix CAS_COUNT_WRITE issue for ICX

From: Xing Zhengjun
Date: Thu Nov 18 2021 - 02:22:38 EST

On 11/18/2021 2:58 PM, Greg KH wrote:
On Thu, Nov 18, 2021 at 10:48:11PM +0800, zhengjun.xing@xxxxxxxxxxxxxxx wrote:
From: Zhengjun Xing <zhengjun.xing@xxxxxxxxxxxxxxx>

The user recently report a perf issue in the ICX platform, when test by
perf event “uncore_imc_x/cas_count_write”,the write bandwidth is always
very small (only 0.38MB/s), it is caused by the wrong "umask" for the
"cas_count_write" event. When double-checking, find "cas_count_read"
also is wrong.

The public document for ICX uncore:

On page 142, Table 2-143, defines Unit Masks for CAS_COUNT:
RD b00001111
WR b00110000

So Corrected both "cas_count_read" and "cas_count_write" for ICX.

Old settings:
INTEL_UNCORE_EVENT_DESC(cas_count_read, "event=0x04,umask=0x03")
INTEL_UNCORE_EVENT_DESC(cas_count_write, "event=0x04,umask=0x0c")

New settings:
INTEL_UNCORE_EVENT_DESC(cas_count_read, "event=0x04,umask=0x0f")
INTEL_UNCORE_EVENT_DESC(cas_count_write, "event=0x04,umask=0x30"),

Fixes: 2b3b76b5ec67 ("perf/x86/intel/uncore: Add Ice Lake server uncore support")
Reviewed-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Signed-off-by: Zhengjun Xing <zhengjun.xing@xxxxxxxxxxxxxxx>
arch/x86/events/intel/uncore_snbep.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 5ddc0f30db6f..a6fd8eb410a9 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -5468,7 +5468,7 @@ static struct intel_uncore_type icx_uncore_imc = {
.fixed_ctr_bits = 48,
- .event_descs = hswep_uncore_imc_events,
+ .event_descs = snr_uncore_imc_events,
.perf_ctr = SNR_IMC_MMIO_PMON_CTR0,
.event_ctl = SNR_IMC_MMIO_PMON_CTL0,


This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
for how to do this properly.


Sorry, I will add "Cc: stable@xxxxxxxxxxxxxxx" in the sign-off area and send the new version patch.

Zhengjun Xing