diff options
Diffstat (limited to 'arch/s390/kernel/perf_cpum_sf.c')
| -rw-r--r-- | arch/s390/kernel/perf_cpum_sf.c | 44 |
1 files changed, 24 insertions, 20 deletions
diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c index b095b1c78987..85a711d783eb 100644 --- a/arch/s390/kernel/perf_cpum_sf.c +++ b/arch/s390/kernel/perf_cpum_sf.c @@ -372,28 +372,33 @@ static void deallocate_buffers(struct cpu_hw_sf *cpuhw) static int allocate_buffers(struct cpu_hw_sf *cpuhw, struct hw_perf_event *hwc) { - unsigned long n_sdb, freq, factor; + unsigned long n_sdb, freq; size_t sample_size; /* Calculate sampling buffers using 4K pages * - * 1. Determine the sample data size which depends on the used - * sampling functions, for example, basic-sampling or - * basic-sampling with diagnostic-sampling. + * 1. The sampling size is 32 bytes for basic sampling. This size + * is the same for all machine types. Diagnostic + * sampling uses auxlilary data buffer setup which provides the + * memory for SDBs using linux common code auxiliary trace + * setup. * - * 2. Use the sampling frequency as input. The sampling buffer is - * designed for almost one second. This can be adjusted through - * the "factor" variable. - * In any case, alloc_sampling_buffer() sets the Alert Request + * 2. Function alloc_sampling_buffer() sets the Alert Request * Control indicator to trigger a measurement-alert to harvest - * sample-data-blocks (sdb). + * sample-data-blocks (SDB). This is done per SDB. This + * measurement alert interrupt fires quick enough to handle + * one SDB, on very high frequency and work loads there might + * be 2 to 3 SBDs available for sample processing. + * Currently there is no need for setup alert request on every + * n-th page. This is counterproductive as one IRQ triggers + * a very high number of samples to be processed at one IRQ. * - * 3. Compute the number of sample-data-blocks and ensure a minimum - * of CPUM_SF_MIN_SDB. Also ensure the upper limit does not - * exceed a "calculated" maximum. The symbolic maximum is - * designed for basic-sampling only and needs to be increased if - * diagnostic-sampling is active. - * See also the remarks for these symbolic constants. + * 3. Use the sampling frequency as input. + * Compute the number of SDBs and ensure a minimum + * of CPUM_SF_MIN_SDB. Depending on frequency add some more + * SDBs to handle a higher sampling rate. + * Use a minimum of CPUM_SF_MIN_SDB and allow for 100 samples + * (one SDB) for every 10000 HZ frequency increment. * * 4. Compute the number of sample-data-block-tables (SDBT) and * ensure a minimum of CPUM_SF_MIN_SDBT (one table can manage up @@ -401,10 +406,7 @@ static int allocate_buffers(struct cpu_hw_sf *cpuhw, struct hw_perf_event *hwc) */ sample_size = sizeof(struct hws_basic_entry); freq = sample_rate_to_freq(&cpuhw->qsi, SAMPL_RATE(hwc)); - factor = 1; - n_sdb = DIV_ROUND_UP(freq, factor * ((PAGE_SIZE-64) / sample_size)); - if (n_sdb < CPUM_SF_MIN_SDB) - n_sdb = CPUM_SF_MIN_SDB; + n_sdb = CPUM_SF_MIN_SDB + DIV_ROUND_UP(freq, 10000); /* If there is already a sampling buffer allocated, it is very likely * that the sampling facility is enabled too. If the event to be @@ -1576,6 +1578,7 @@ static void hw_collect_aux(struct cpu_hw_sf *cpuhw) unsigned long range = 0, size; unsigned long long overflow = 0; struct perf_output_handle *handle = &cpuhw->handle; + unsigned long num_sdb; aux = perf_get_aux(handle); if (WARN_ON_ONCE(!aux)) @@ -1587,13 +1590,14 @@ static void hw_collect_aux(struct cpu_hw_sf *cpuhw) size >> PAGE_SHIFT); perf_aux_output_end(handle, size); + num_sdb = aux->sfb.num_sdb; while (!done) { /* Get an output handle */ aux = perf_aux_output_begin(handle, cpuhw->event); if (handle->size == 0) { pr_err("The AUX buffer with %lu pages for the " "diagnostic-sampling mode is full\n", - aux->sfb.num_sdb); + num_sdb); debug_sprintf_event(sfdbg, 1, "%s: AUX buffer used up\n", __func__); |