87ed2b7f5a
The block cache implementation in loader has proven to be almost useless, and in worst case even slowing down the disk reads due to insufficient cache size and extra memory copy. Also the current cache implementation does not cache reads from CDs, or work with zfs built on top of multiple disks. Instead of an LRU, this code uses a simple hash (O(1) read from cache), and instead of a single global cache, a separate cache per block device. The cache also implements limited read-ahead to increase performance. To simplify read ahead management, the read ahead will not wrap over bcache end, so in worst case, single block physical read will be performed to fill the last block in bcache. Booting from a virtual CD over IPMI: 0ms latency, before: 27 second, after: 7 seconds 60ms latency, before: over 12 minutes, after: under 5 minutes. Submitted by: Toomas Soome <tsoome@me.com> Reviewed by: delphij (previous version), emaste (previous version) Relnotes: yes Differential Revision: https://reviews.freebsd.org/D4713
152 lines
3.5 KiB
C
152 lines
3.5 KiB
C
/*-
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* Copyright (c) 2009 Marcel Moolenaar
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* All rights reserved.
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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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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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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
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* FOR 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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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <stand.h>
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#include <sys/param.h>
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#include <sys/endian.h>
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#include <sys/queue.h>
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#include <machine/stdarg.h>
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#include "bootstrap.h"
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#define MD_BLOCK_SIZE 512
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#ifndef MD_IMAGE_SIZE
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#error Must be compiled with MD_IMAGE_SIZE defined
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#endif
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#if (MD_IMAGE_SIZE == 0 || MD_IMAGE_SIZE % MD_BLOCK_SIZE)
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#error Image size must be a multiple of 512.
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#endif
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/*
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* Preloaded image gets put here.
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* Applications that patch the object with the image can determine
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* the size looking at the start and end markers (strings),
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* so we want them contiguous.
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*/
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static struct {
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u_char start[MD_IMAGE_SIZE];
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u_char end[128];
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} md_image = {
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.start = "MFS Filesystem goes here",
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.end = "MFS Filesystem had better STOP here",
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};
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/* devsw I/F */
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static int md_init(void);
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static int md_strategy(void *, int, daddr_t, size_t, size_t, char *, size_t *);
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static int md_open(struct open_file *, ...);
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static int md_close(struct open_file *);
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static void md_print(int);
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struct devsw md_dev = {
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"md",
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DEVT_DISK,
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md_init,
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md_strategy,
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md_open,
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md_close,
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noioctl,
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md_print
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};
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static int
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md_init(void)
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{
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return (0);
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}
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static int
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md_strategy(void *devdata, int rw, daddr_t blk, size_t offset, size_t size,
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char *buf, size_t *rsize)
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{
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struct devdesc *dev = (struct devdesc *)devdata;
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size_t ofs;
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if (dev->d_unit != 0)
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return (ENXIO);
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if (blk < 0 || blk >= (MD_IMAGE_SIZE / MD_BLOCK_SIZE))
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return (EIO);
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if (size % MD_BLOCK_SIZE)
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return (EIO);
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ofs = blk * MD_BLOCK_SIZE;
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if ((ofs + size) > MD_IMAGE_SIZE)
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size = MD_IMAGE_SIZE - ofs;
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if (rsize != 0)
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*rsize = size;
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switch (rw) {
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case F_READ:
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bcopy(md_image.start + ofs, buf, size);
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return (0);
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case F_WRITE:
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bcopy(buf, md_image.start + ofs, size);
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return (0);
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}
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return (ENODEV);
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}
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static int
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md_open(struct open_file *f, ...)
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{
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va_list ap;
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struct devdesc *dev;
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va_start(ap, f);
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dev = va_arg(ap, struct devdesc *);
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va_end(ap);
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if (dev->d_unit != 0)
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return (ENXIO);
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return (0);
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}
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static int
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md_close(struct open_file *f)
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{
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struct devdesc *dev;
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dev = (struct devdesc *)(f->f_devdata);
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return ((dev->d_unit != 0) ? ENXIO : 0);
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}
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static void
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md_print(int verbose)
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{
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printf("MD (%u bytes)\n", MD_IMAGE_SIZE);
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}
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