3b18152c32
- Adjust slice values - Instead of one async queue, one is defined per priority level. This prevents kernel threads (such as reiserfs/x and others) that run at higher io priority from conflicting with others. Previously, it was a coin toss what io prio the async queue got, it was defined by who first set up the queue. - Let a time slice only begin, when the previous slice is completely done. Previously we could be somewhat unfair to a new sync slice, if the previous slice was async and had several ios queued. This might need a little tweaking if throughput suffers a little due to this, allowing perhaps an overlap of a single request or so. - Optimize the calling of kblockd_schedule_work() by doing it only when it is strictly necessary (no requests in driver and work left to do). - Correct sync vs async logic. A 'normal' process can be purely async as well, and a flusher can be purely sync as well. Sync or async is now a property of the class defined and requests pending. Previously writers could be considered sync, when they were really async. - Get rid of the bit fields in cfqq and crq, use flags instead. - Various other cleanups and fixes Signed-off-by: Jens Axboe <axboe@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
88 lines
2.1 KiB
C
88 lines
2.1 KiB
C
#ifndef IOPRIO_H
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#define IOPRIO_H
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#include <linux/sched.h>
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/*
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* Gives us 8 prio classes with 13-bits of data for each class
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*/
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#define IOPRIO_BITS (16)
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#define IOPRIO_CLASS_SHIFT (13)
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#define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1)
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#define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
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#define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK)
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#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
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#define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
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/*
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* These are the io priority groups as implemented by CFQ. RT is the realtime
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* class, it always gets premium service. BE is the best-effort scheduling
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* class, the default for any process. IDLE is the idle scheduling class, it
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* is only served when no one else is using the disk.
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*/
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enum {
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IOPRIO_CLASS_NONE,
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IOPRIO_CLASS_RT,
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IOPRIO_CLASS_BE,
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IOPRIO_CLASS_IDLE,
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};
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/*
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* 8 best effort priority levels are supported
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*/
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#define IOPRIO_BE_NR (8)
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asmlinkage int sys_ioprio_set(int, int, int);
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asmlinkage int sys_ioprio_get(int, int);
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enum {
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IOPRIO_WHO_PROCESS = 1,
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IOPRIO_WHO_PGRP,
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IOPRIO_WHO_USER,
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};
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/*
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* if process has set io priority explicitly, use that. if not, convert
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* the cpu scheduler nice value to an io priority
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*/
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#define IOPRIO_NORM (4)
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static inline int task_ioprio(struct task_struct *task)
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{
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WARN_ON(!ioprio_valid(task->ioprio));
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return IOPRIO_PRIO_DATA(task->ioprio);
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}
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static inline int task_nice_ioprio(struct task_struct *task)
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{
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return (task_nice(task) + 20) / 5;
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}
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/*
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* For inheritance, return the highest of the two given priorities
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*/
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static inline int ioprio_best(unsigned short aprio, unsigned short bprio)
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{
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unsigned short aclass = IOPRIO_PRIO_CLASS(aprio);
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unsigned short bclass = IOPRIO_PRIO_CLASS(bprio);
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if (!ioprio_valid(aprio))
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return bprio;
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if (!ioprio_valid(bprio))
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return aprio;
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if (aclass == IOPRIO_CLASS_NONE)
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aclass = IOPRIO_CLASS_BE;
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if (bclass == IOPRIO_CLASS_NONE)
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bclass = IOPRIO_CLASS_BE;
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if (aclass == bclass)
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return min(aprio, bprio);
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if (aclass > bclass)
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return bprio;
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else
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return aprio;
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}
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#endif
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