Messages in this thread | | | From | Ingo Molnar <> | Date | Wed, 6 May 2015 12:02:11 +0200 | Subject | Re: [PATCH 2/2] x86/quark: Add Quark embedded SRAM self-test |
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* Bryan O'Donoghue <pure.logic@nexus-software.ie> wrote:
> +/** > + * esram_self_test_time > + * > + * This function is carefully constructed to measure and verify the > + * performance boost provided by eSRAM. We invalidate the cache with a > + * wbinvd() and then perform a series of reads - each of which will cause a > + * cacheline miss. We measure the aggregate time it takes to complete the > + * series of reads and return the delta in cycles. The calling function will > + * pass either a pointer to DRAM or a pointer to eSRAM. > + * > + * @param walker: Pointer to RAM area to test. > + * @return: Number of cycles to complete test. > + */ > +static cycles_t esram_self_test_time(char *walker, ssize_t step, ssize_t size) > +{ > + volatile u32 dummy = 0; > + int i; > + int j; > + cycle_t t1; > + cycle_t t2; > + u32 page_count = size / PAGE_SIZE; > + > + local_irq_disable(); > + t1 = get_cycles(); > + for (i = 0; i < page_count; i++) { > + for (j = 0; j < PAGE_SIZE/step; j++) { > + dummy += *(u32 *)walker; > + walker += step; > + } > + } > + t2 = get_cycles(); > + local_irq_enable(); > + > + return t2 > t1 ? t2 - t1 : ULLONG_MAX - t2 + t1; > +}
So I don't see the wbinvd() that the description mentions.
> + * esram_self_test_init - entry point for IMR driver. > + * esram_self_test_exit - exit point for IMR code.
Stale 'IMR' references left over from copy & paste?
Thanks,
Ingo
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