函数逻辑报告

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:block\blk-iolatency.c Create Date:2022-07-27 19:20:56
Last Modify:2020-03-12 14:18:49 Copyright©Brick
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函数名称：We scale the qd down faster than we scale up, so we need to use this helper* to adjust the scale_cookie accordingly so we don't prematurely get* scale_cookie at DEFAULT_SCALE_COOKIE and unthrottle too much

函数原型：static void scale_cookie_change(struct blk_iolatency *blkiolat, struct child_latency_info *lat_info, bool up)

返回类型：void

参数：

类型参数名称
struct blk_iolatency *blkiolat
struct child_latency_info *lat_info
boolup
327  qd等于 Max # of requests
328  scale等于scale_amount(qd, up)
329  old等于atomic_read( & Cookie to tell if we need to scale up or down. )
330  max_scale等于qd左移1位
331  diff等于0
333  如果old小于DEFAULT_SCALE_COOKIE则diff等于DEFAULT_SCALE_COOKIE减old
336  如果up则
337  如果scale加old大于DEFAULT_SCALE_COOKIE则atomic_set( & Cookie to tell if we need to scale up or down. , DEFAULT_SCALE_COOKIE)
340  否则如果diff大于qd则atomic_inc( & Cookie to tell if we need to scale up or down. )
342  否则atomic_add(scale, & Cookie to tell if we need to scale up or down. )
344  否则
351  如果diff大于qd则
352  如果diff小于max_scale则atomic_dec( & Cookie to tell if we need to scale up or down. )
354  否则
355  atomic_sub(scale, & Cookie to tell if we need to scale up or down. )
调用者
名称描述
iolatency_check_latencies
blkiolatency_timer_fn