[LTP] pmc_core: add test for pkgc_blocker_residency_show

[linuxtestproject.agent@gmail.com]

Hi Piotr,

On August 11, 2026, Piotr Kubaj wrote:
> pmc_core: add test for pkgc_blocker_residency_show

> 	/*
> 	 * Interval between the two samples. The PMT telemetry region behind these
> 	 * counters refreshes at roughly 1s granularity: measured on Nova Lake, no
> 	 * counter moved over 200ms or 500ms, while 5 of 28 moved over 1s. Sample well
> 	 * past that so a static counter means "idle source", not "not refreshed yet".
> 	 */
> 	#define SAMPLE_DELAY_US 2000000
> 	...
> 	usleep(SAMPLE_DELAY_US);

Could this use bounded exponential-backoff polling instead? The fixed sleep is
being used to synchronize the second sample with the asynchronous telemetry
refresh, which violates the no sleep-based synchronization rule.

> 		if (sscanf(line, "%63s %u", name, &value) != 2) {
> 			tst_res(TFAIL, "malformed counter line: '%s'", line);
> 			continue;
> 		}
>
> 		if (strncmp(name, PREFIX, sizeof(PREFIX) - 1)) {

Could this validate the complete line and require a nonempty source suffix?
The current conversion accepts signed values, trailing tokens, and the bare
name "PKGC_BLOCK_RESIDENCY_". If both snapshots contain such a line, it is
recorded as a valid counter and the test can pass despite malformed output.

> 	.needs_root = 1,

Could the high-level description explain why root is required? Tests setting
needs_root must document the reason in the exported test description.

>  high_freq_hwp_cap_cppc
>  cpufreq_intel
>  rfim01
> +pkgc_blocker_residency_show

Could the new entry be inserted alphabetically? Leaf .gitignore entries are
required to remain sorted.

Verdict - Needs revision

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