e5436ab5af
It's often useful to have a callback when an I/O takes more than a threshold amount of time. This adds the infrastructure for periph devices to register one. One use-case is as a debugging aide when you need a semi-realtime indication of an I/O outlier so you can trigger bus capture gear for vendor analysis. Sponsored by: Netflix, Inc
107 lines
4.3 KiB
C
107 lines
4.3 KiB
C
/*-
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* CAM IO Scheduler Interface
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*
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2015 Netflix, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions, and the following disclaimer,
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* without modification, immediately at the beginning of the file.
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* 2. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _CAM_CAM_IOSCHED_H
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#define _CAM_CAM_IOSCHED_H
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/* No user-serviceable parts in here. */
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#ifdef _KERNEL
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/* Forward declare all structs to keep interface thin */
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struct cam_iosched_softc;
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struct sysctl_ctx_list;
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struct sysctl_oid;
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union ccb;
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struct bio;
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/*
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* For 64-bit platforms, we know that uintptr_t is the same size as sbintime_t
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* so we can store values in it. For 32-bit systems, however, uintptr_t is only
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* 32-bits, so it won't fit. For those systems, store 24 bits of fraction and 8
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* bits of seconds. This allows us to measure an interval of up to ~256s, which
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* is ~200x what our current uses require. Provide some convenience functions to
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* get the time, subtract two times and convert back to sbintime_t in a safe way
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* that can be centralized.
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*/
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#ifdef __LP64__
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#define CAM_IOSCHED_TIME_SHIFT 0
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#else
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#define CAM_IOSCHED_TIME_SHIFT 8
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#endif
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static inline uintptr_t
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cam_iosched_now(void)
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{
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/* Cast here is to avoid right shifting a signed value */
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return (uintptr_t)((uint64_t)sbinuptime() >> CAM_IOSCHED_TIME_SHIFT);
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}
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static inline uintptr_t
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cam_iosched_delta_t(uintptr_t then)
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{
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/* Since the types are identical, wrapping works correctly */
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return (cam_iosched_now() - then);
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}
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static inline sbintime_t
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cam_iosched_sbintime_t(uintptr_t delta)
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{
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/* Cast here is to widen the type so the left shift doesn't lose precision */
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return (sbintime_t)((uint64_t)delta << CAM_IOSCHED_TIME_SHIFT);
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}
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typedef void (*cam_iosched_latfcn_t)(void *, sbintime_t, struct bio *);
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int cam_iosched_init(struct cam_iosched_softc **, struct cam_periph *periph);
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void cam_iosched_fini(struct cam_iosched_softc *);
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void cam_iosched_sysctl_init(struct cam_iosched_softc *, struct sysctl_ctx_list *, struct sysctl_oid *);
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struct bio *cam_iosched_next_trim(struct cam_iosched_softc *isc);
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struct bio *cam_iosched_get_trim(struct cam_iosched_softc *isc);
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struct bio *cam_iosched_next_bio(struct cam_iosched_softc *isc);
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void cam_iosched_queue_work(struct cam_iosched_softc *isc, struct bio *bp);
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void cam_iosched_flush(struct cam_iosched_softc *isc, struct devstat *stp, int err);
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void cam_iosched_schedule(struct cam_iosched_softc *isc, struct cam_periph *periph);
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void cam_iosched_finish_trim(struct cam_iosched_softc *isc);
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void cam_iosched_submit_trim(struct cam_iosched_softc *isc);
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void cam_iosched_put_back_trim(struct cam_iosched_softc *isc, struct bio *bp);
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void cam_iosched_set_sort_queue(struct cam_iosched_softc *isc, int val);
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int cam_iosched_has_work_flags(struct cam_iosched_softc *isc, uint32_t flags);
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void cam_iosched_set_work_flags(struct cam_iosched_softc *isc, uint32_t flags);
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void cam_iosched_clr_work_flags(struct cam_iosched_softc *isc, uint32_t flags);
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void cam_iosched_trim_done(struct cam_iosched_softc *isc);
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int cam_iosched_bio_complete(struct cam_iosched_softc *isc, struct bio *bp, union ccb *done_ccb);
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void cam_iosched_set_latfcn(struct cam_iosched_softc *isc, cam_iosched_latfcn_t, void *);
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#endif
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#endif
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