bfq_update_peak_rate

Name:Update the read/write peak rate (the main quantity used for* auto-tuning, see update_thr_responsiveness_params())

Proto:static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)

Type:void

Parameter:

Type	Parameter	Name
struct bfq_data *	bfqd
struct request *	rq

3180

now_ns = ktime_get_ns()

3182

If number of samples in current observation interval == 0 Then

3183

bfq_log(bfqd, "update_peak_rate: goto reset, samples %d", number of samples in current observation interval )

3185

bfq_reset_rate_computation(bfqd, rq)

3186

Go to update_last_values

3201

If now_ns - time of last rq dispatch in current observation interval (ns) > 100 * NSEC_PER_MSEC && number of requests dispatched and waiting for completion == 0 Then Go to update_rate_and_reset

3206

number of samples in current observation interval ++

3208

If ( number of requests dispatched and waiting for completion > 0 || now_ns - time of last request completion (ns) < Below this threshold (in ns), we consider thinktime immediate. ) && Not BFQ_RQ_SEEKY(bfqd, on-disk position of the last served request , rq) Then num of samples of seq dispatches in current observation interval ++

3213

total num of sectors transferred in current observation interval += blk_rq_sectors(rq)

3216

If Value is more likely to compile time( number of samples in current observation interval % 32) Then max rq size seen during current observation interval (sectors) = max_t - return maximum of two values, using the specified type*@type: data type to use*@x: first value*@y: second value(u32, blk_rq_sectors(rq), max rq size seen during current observation interval (sectors) )

3219

Else max rq size seen during current observation interval (sectors) = blk_rq_sectors(rq)

3222

time elapsed from first dispatch in current observ. interval (us) = now_ns - time of first rq dispatch in current observation interval (ns)

3225

If time elapsed from first dispatch in current observ. interval (us) < Target observation time interval for a peak-rate update (ns) Then Go to update_last_values

3228

update_rate_and_reset :

3229

bfq_update_rate_reset(bfqd, rq)

3230

update_last_values :

3231

on-disk position of the last served request = lk_rq_pos() : the current sector* blk_rq_bytes() : bytes left in the entire request* blk_rq_cur_bytes() : bytes left in the current segment* blk_rq_err_bytes() : bytes left till the next error boundary* blk_rq_sectors() : sectors left in the entire + blk_rq_sectors(rq)

3232

If RQ_BFQQ(rq) == bfq_queue in service Then position of the last served request for the in-service queue = on-disk position of the last served request

3234

time of last rq dispatch in current observation interval (ns) = now_ns

**Caller**
Name	Describe
bfq_dispatch_remove	Remove request from internal lists.

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