lib/dim/dim.c

Source file repositories/reference/linux-study-clean/lib/dim/dim.c

File Facts

System
Linux kernel
Corpus path
lib/dim/dim.c
Extension
.c
Size
2263 bytes
Lines
89
Domain
Kernel Services
Bucket
lib
Inferred role
Kernel Services: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Shared kernel service surface used by multiple subsystems, including helpers, cryptography, virtualization support, and async I/O infrastructure.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
/*
 * Copyright (c) 2019, Mellanox Technologies inc.  All rights reserved.
 */

#include <linux/dim.h>

bool dim_on_top(struct dim *dim)
{
	switch (dim->tune_state) {
	case DIM_PARKING_ON_TOP:
	case DIM_PARKING_TIRED:
		return true;
	case DIM_GOING_RIGHT:
		return (dim->steps_left > 1) && (dim->steps_right == 1);
	default: /* DIM_GOING_LEFT */
		return (dim->steps_right > 1) && (dim->steps_left == 1);
	}
}
EXPORT_SYMBOL(dim_on_top);

void dim_turn(struct dim *dim)
{
	switch (dim->tune_state) {
	case DIM_PARKING_ON_TOP:
	case DIM_PARKING_TIRED:
		break;
	case DIM_GOING_RIGHT:
		dim->tune_state = DIM_GOING_LEFT;
		dim->steps_left = 0;
		break;
	case DIM_GOING_LEFT:
		dim->tune_state = DIM_GOING_RIGHT;
		dim->steps_right = 0;
		break;
	}
}
EXPORT_SYMBOL(dim_turn);

void dim_park_on_top(struct dim *dim)
{
	dim->steps_right  = 0;
	dim->steps_left   = 0;
	dim->tired        = 0;
	dim->tune_state   = DIM_PARKING_ON_TOP;
}
EXPORT_SYMBOL(dim_park_on_top);

void dim_park_tired(struct dim *dim)
{
	dim->steps_right  = 0;
	dim->steps_left   = 0;
	dim->tune_state   = DIM_PARKING_TIRED;
}
EXPORT_SYMBOL(dim_park_tired);

bool dim_calc_stats(const struct dim_sample *start,
		    const struct dim_sample *end,
		    struct dim_stats *curr_stats)
{
	/* u32 holds up to 71 minutes, should be enough */
	u32 delta_us = ktime_us_delta(end->time, start->time);
	u32 npkts = BIT_GAP(BITS_PER_TYPE(u32), end->pkt_ctr, start->pkt_ctr);
	u32 nbytes = BIT_GAP(BITS_PER_TYPE(u32), end->byte_ctr,
			     start->byte_ctr);
	u32 ncomps = BIT_GAP(BITS_PER_TYPE(u32), end->comp_ctr,
			     start->comp_ctr);

	if (!delta_us)
		return false;

	curr_stats->ppms = DIV_ROUND_UP(npkts * USEC_PER_MSEC, delta_us);
	curr_stats->bpms = DIV_ROUND_UP(nbytes * USEC_PER_MSEC, delta_us);
	curr_stats->epms = DIV_ROUND_UP(DIM_NEVENTS * USEC_PER_MSEC,
					delta_us);
	curr_stats->cpms = DIV_ROUND_UP(ncomps * USEC_PER_MSEC, delta_us);
	if (curr_stats->epms != 0)
		curr_stats->cpe_ratio = DIV_ROUND_DOWN_ULL(
			curr_stats->cpms * 100, curr_stats->epms);
	else
		curr_stats->cpe_ratio = 0;

	return true;
}
EXPORT_SYMBOL(dim_calc_stats);

MODULE_DESCRIPTION("Dynamic Interrupt Moderation (DIM) library");
MODULE_LICENSE("Dual BSD/GPL");

Annotation

Implementation Notes