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linux-stable/drivers/mtd/tests/speedtest.c
Amit Kumar Mahapatra ceef4cf97b mtd: tests: Fix eraseblock read speed miscalculation for lower partition sizes 
While calculating speed during  mtd_speedtest, the time interval
(i.e., start - finish) is rounded off to the nearest milliseconds by
ignoring the fractional part. This leads to miscalculation of speed.
The miscalculation is more visible while running speed test on small
partition sizes(i.e., when partition size is equal to eraseblock size or
twice the eraseblock size) at higher spi frequencies.

For e.g., while calculating eraseblock read speed for a mtd partition with
size equal to the eraseblock size(i.e., 64KiB) the eraseblock read time
interval comes out to be 966490 nanosecond. This is then converted to
millisecond(i.e., 0.966 msec.). The integer part (i.e., 0 msec) of the
value is considered and the fractional part (i.e., 0.966) is ignored,for
calculating the eraseblock read speed. So the reported eraseblock read
speed is 0 KiB/s, which is incorrect.

There are two approaches to fix this issue.

First approach will be to keep the time interval in millisecond. and round
up the integer value, with this approach the 0.966msec time interval in the
above example will be rounded up to 1msec and this value is used for
calculating the speed. Downside of this approach is that the reported speed
is still not accurate.

Second approach will be to convert the time interval to microseconds
instead of milliseconds, with this approach the 966490 nanosecond time
interval in the above example will be converted t0 966.490usec and this
value is used for calculating the speed. As compared to the current
implementation and the suggested First approach, this approach will report
a more accurate speed. Downside of this approach is that, in future if the
mtd size is too large then the u64 variable, that holds the number of
bytes, might overflow.

In this patch we have gone with the second approach as this reports a more
accurate speed. With this approach the eraseblock read speed in the above
example comes out to be 132505 KiB/s when the spi clock is configured at
150Mhz.

Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@xilinx.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220208103905.13354-1-amit.kumar-mahapatra@xilinx.com
2022-03-14 17:01:47 +01:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2007 Nokia Corporation
*
* Test read and write speed of a MTD device.
*
* Author: Adrian Hunter <adrian.hunter@nokia.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/ktime.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/err.h>
#include <linux/mtd/mtd.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/random.h>
#include "mtd_test.h"
static int dev = -EINVAL;
module_param(dev, int, S_IRUGO);
MODULE_PARM_DESC(dev, "MTD device number to use");
static int count;
module_param(count, int, S_IRUGO);
MODULE_PARM_DESC(count, "Maximum number of eraseblocks to use "
"(0 means use all)");
static struct mtd_info *mtd;
static unsigned char *iobuf;
static unsigned char *bbt;
static int pgsize;
static int ebcnt;
static int pgcnt;
static int goodebcnt;
static ktime_t start, finish;
static int multiblock_erase(int ebnum, int blocks)
{
int err;
struct erase_info ei;
loff_t addr = (loff_t)ebnum * mtd->erasesize;
memset(&ei, 0, sizeof(struct erase_info));
ei.addr = addr;
ei.len = mtd->erasesize * blocks;
err = mtd_erase(mtd, &ei);
if (err) {
pr_err("error %d while erasing EB %d, blocks %d\n",
err, ebnum, blocks);
return err;
}
return 0;
}
static int write_eraseblock(int ebnum)
{
loff_t addr = (loff_t)ebnum * mtd->erasesize;
return mtdtest_write(mtd, addr, mtd->erasesize, iobuf);
}
static int write_eraseblock_by_page(int ebnum)
{
int i, err = 0;
loff_t addr = (loff_t)ebnum * mtd->erasesize;
void *buf = iobuf;
for (i = 0; i < pgcnt; i++) {
err = mtdtest_write(mtd, addr, pgsize, buf);
if (err)
break;
addr += pgsize;
buf += pgsize;
}
return err;
}
static int write_eraseblock_by_2pages(int ebnum)
{
size_t sz = pgsize * 2;
int i, n = pgcnt / 2, err = 0;
loff_t addr = (loff_t)ebnum * mtd->erasesize;
void *buf = iobuf;
for (i = 0; i < n; i++) {
err = mtdtest_write(mtd, addr, sz, buf);
if (err)
return err;
addr += sz;
buf += sz;
}
if (pgcnt % 2)
err = mtdtest_write(mtd, addr, pgsize, buf);
return err;
}
static int read_eraseblock(int ebnum)
{
loff_t addr = (loff_t)ebnum * mtd->erasesize;
return mtdtest_read(mtd, addr, mtd->erasesize, iobuf);
}
static int read_eraseblock_by_page(int ebnum)
{
int i, err = 0;
loff_t addr = (loff_t)ebnum * mtd->erasesize;
void *buf = iobuf;
for (i = 0; i < pgcnt; i++) {
err = mtdtest_read(mtd, addr, pgsize, buf);
if (err)
break;
addr += pgsize;
buf += pgsize;
}
return err;
}
static int read_eraseblock_by_2pages(int ebnum)
{
size_t sz = pgsize * 2;
int i, n = pgcnt / 2, err = 0;
loff_t addr = (loff_t)ebnum * mtd->erasesize;
void *buf = iobuf;
for (i = 0; i < n; i++) {
err = mtdtest_read(mtd, addr, sz, buf);
if (err)
return err;
addr += sz;
buf += sz;
}
if (pgcnt % 2)
err = mtdtest_read(mtd, addr, pgsize, buf);
return err;
}
static inline void start_timing(void)
{
start = ktime_get();
}
static inline void stop_timing(void)
{
finish = ktime_get();
}
static long calc_speed(void)
{
uint64_t k, us;
us = ktime_us_delta(finish, start);
if (us == 0)
return 0;
k = (uint64_t)goodebcnt * (mtd->erasesize / 1024) * 1000000;
do_div(k, us);
return k;
}
static int __init mtd_speedtest_init(void)
{
int err, i, blocks, j, k;
long speed;
uint64_t tmp;
printk(KERN_INFO "\n");
printk(KERN_INFO "=================================================\n");
if (dev < 0) {
pr_info("Please specify a valid mtd-device via module parameter\n");
pr_crit("CAREFUL: This test wipes all data on the specified MTD device!\n");
return -EINVAL;
}
if (count)
pr_info("MTD device: %d count: %d\n", dev, count);
else
pr_info("MTD device: %d\n", dev);
mtd = get_mtd_device(NULL, dev);
if (IS_ERR(mtd)) {
err = PTR_ERR(mtd);
pr_err("error: cannot get MTD device\n");
return err;
}
if (mtd->writesize == 1) {
pr_info("not NAND flash, assume page size is 512 "
"bytes.\n");
pgsize = 512;
} else
pgsize = mtd->writesize;
tmp = mtd->size;
do_div(tmp, mtd->erasesize);
ebcnt = tmp;
pgcnt = mtd->erasesize / pgsize;
pr_info("MTD device size %llu, eraseblock size %u, "
"page size %u, count of eraseblocks %u, pages per "
"eraseblock %u, OOB size %u\n",
(unsigned long long)mtd->size, mtd->erasesize,
pgsize, ebcnt, pgcnt, mtd->oobsize);
if (count > 0 && count < ebcnt)
ebcnt = count;
err = -ENOMEM;
iobuf = kmalloc(mtd->erasesize, GFP_KERNEL);
if (!iobuf)
goto out;
prandom_bytes(iobuf, mtd->erasesize);
bbt = kzalloc(ebcnt, GFP_KERNEL);
if (!bbt)
goto out;
err = mtdtest_scan_for_bad_eraseblocks(mtd, bbt, 0, ebcnt);
if (err)
goto out;
for (i = 0; i < ebcnt; i++) {
if (!bbt[i])
goodebcnt++;
}
err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
if (err)
goto out;
/* Write all eraseblocks, 1 eraseblock at a time */
pr_info("testing eraseblock write speed\n");
start_timing();
for (i = 0; i < ebcnt; ++i) {
if (bbt[i])
continue;
err = write_eraseblock(i);
if (err)
goto out;
err = mtdtest_relax();
if (err)
goto out;
}
stop_timing();
speed = calc_speed();
pr_info("eraseblock write speed is %ld KiB/s\n", speed);
/* Read all eraseblocks, 1 eraseblock at a time */
pr_info("testing eraseblock read speed\n");
start_timing();
for (i = 0; i < ebcnt; ++i) {
if (bbt[i])
continue;
err = read_eraseblock(i);
if (err)
goto out;
err = mtdtest_relax();
if (err)
goto out;
}
stop_timing();
speed = calc_speed();
pr_info("eraseblock read speed is %ld KiB/s\n", speed);
err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
if (err)
goto out;
/* Write all eraseblocks, 1 page at a time */
pr_info("testing page write speed\n");
start_timing();
for (i = 0; i < ebcnt; ++i) {
if (bbt[i])
continue;
err = write_eraseblock_by_page(i);
if (err)
goto out;
err = mtdtest_relax();
if (err)
goto out;
}
stop_timing();
speed = calc_speed();
pr_info("page write speed is %ld KiB/s\n", speed);
/* Read all eraseblocks, 1 page at a time */
pr_info("testing page read speed\n");
start_timing();
for (i = 0; i < ebcnt; ++i) {
if (bbt[i])
continue;
err = read_eraseblock_by_page(i);
if (err)
goto out;
err = mtdtest_relax();
if (err)
goto out;
}
stop_timing();
speed = calc_speed();
pr_info("page read speed is %ld KiB/s\n", speed);
err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
if (err)
goto out;
/* Write all eraseblocks, 2 pages at a time */
pr_info("testing 2 page write speed\n");
start_timing();
for (i = 0; i < ebcnt; ++i) {
if (bbt[i])
continue;
err = write_eraseblock_by_2pages(i);
if (err)
goto out;
err = mtdtest_relax();
if (err)
goto out;
}
stop_timing();
speed = calc_speed();
pr_info("2 page write speed is %ld KiB/s\n", speed);
/* Read all eraseblocks, 2 pages at a time */
pr_info("testing 2 page read speed\n");
start_timing();
for (i = 0; i < ebcnt; ++i) {
if (bbt[i])
continue;
err = read_eraseblock_by_2pages(i);
if (err)
goto out;
err = mtdtest_relax();
if (err)
goto out;
}
stop_timing();
speed = calc_speed();
pr_info("2 page read speed is %ld KiB/s\n", speed);
/* Erase all eraseblocks */
pr_info("Testing erase speed\n");
start_timing();
err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
if (err)
goto out;
stop_timing();
speed = calc_speed();
pr_info("erase speed is %ld KiB/s\n", speed);
/* Multi-block erase all eraseblocks */
for (k = 1; k < 7; k++) {
blocks = 1 << k;
pr_info("Testing %dx multi-block erase speed\n",
blocks);
start_timing();
for (i = 0; i < ebcnt; ) {
for (j = 0; j < blocks && (i + j) < ebcnt; j++)
if (bbt[i + j])
break;
if (j < 1) {
i++;
continue;
}
err = multiblock_erase(i, j);
if (err)
goto out;
err = mtdtest_relax();
if (err)
goto out;
i += j;
}
stop_timing();
speed = calc_speed();
pr_info("%dx multi-block erase speed is %ld KiB/s\n",
blocks, speed);
}
pr_info("finished\n");
out:
kfree(iobuf);
kfree(bbt);
put_mtd_device(mtd);
if (err)
pr_info("error %d occurred\n", err);
printk(KERN_INFO "=================================================\n");
return err;
}
module_init(mtd_speedtest_init);
static void __exit mtd_speedtest_exit(void)
{
return;
}
module_exit(mtd_speedtest_exit);
MODULE_DESCRIPTION("Speed test module");
MODULE_AUTHOR("Adrian Hunter");
MODULE_LICENSE("GPL");
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