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

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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:

https://www.intel.com/content/www/us/en/develop/download/3rd-gen-intel-xeon-processor-scalable-uncore-pm.html

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

New settings:
  snr_uncore_imc_events
	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,
  	.fixed_ctr	= SNR_IMC_MMIO_PMON_FIXED_CTR,
  	.fixed_ctl	= SNR_IMC_MMIO_PMON_FIXED_CTL,
-	.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,
  	.event_mask	= SNBEP_PMON_RAW_EVENT_MASK,
--
2.25.1

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
     https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

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

--
Zhengjun Xing



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