Current Path : /sys/boot/common/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
Current File : //sys/boot/common/bcache.c |
/*- * Copyright (c) 1998 Michael Smith <msmith@freebsd.org> * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD: release/9.1.0/sys/boot/common/bcache.c 136097 2004-10-03 16:34:01Z stefanf $"); /* * Simple LRU block cache */ #include <sys/stdint.h> #include <stand.h> #include <string.h> #include <bitstring.h> #include "bootstrap.h" /* #define BCACHE_DEBUG */ #ifdef BCACHE_DEBUG #define BCACHE_TIMEOUT 10 # define DEBUG(fmt, args...) printf("%s: " fmt "\n" , __func__ , ## args) #else #define BCACHE_TIMEOUT 2 # define DEBUG(fmt, args...) #endif struct bcachectl { daddr_t bc_blkno; time_t bc_stamp; int bc_count; }; static struct bcachectl *bcache_ctl; static caddr_t bcache_data; static bitstr_t *bcache_miss; static u_int bcache_nblks; static u_int bcache_blksize; static u_int bcache_hits, bcache_misses, bcache_ops, bcache_bypasses; static u_int bcache_flushes; static u_int bcache_bcount; static void bcache_invalidate(daddr_t blkno); static void bcache_insert(caddr_t buf, daddr_t blkno); static int bcache_lookup(caddr_t buf, daddr_t blkno); /* * Initialise the cache for (nblks) of (bsize). */ int bcache_init(u_int nblks, size_t bsize) { /* discard any old contents */ if (bcache_data != NULL) { free(bcache_data); bcache_data = NULL; free(bcache_ctl); } /* Allocate control structures */ bcache_nblks = nblks; bcache_blksize = bsize; bcache_data = malloc(bcache_nblks * bcache_blksize); bcache_ctl = (struct bcachectl *)malloc(bcache_nblks * sizeof(struct bcachectl)); bcache_miss = bit_alloc((bcache_nblks + 1) / 2); if ((bcache_data == NULL) || (bcache_ctl == NULL) || (bcache_miss == NULL)) { if (bcache_miss) free(bcache_miss); if (bcache_ctl) free(bcache_ctl); if (bcache_data) free(bcache_data); bcache_data = NULL; return(ENOMEM); } return(0); } /* * Flush the cache */ void bcache_flush(void) { u_int i; bcache_flushes++; /* Flush the cache */ for (i = 0; i < bcache_nblks; i++) { bcache_ctl[i].bc_count = -1; bcache_ctl[i].bc_blkno = -1; } } /* * Handle a write request; write directly to the disk, and populate the * cache with the new values. */ static int write_strategy(void *devdata, int unit, int rw, daddr_t blk, size_t size, char *buf, size_t *rsize) { struct bcache_devdata *dd = (struct bcache_devdata *)devdata; daddr_t i, nblk; int err; nblk = size / bcache_blksize; /* Invalidate the blocks being written */ for (i = 0; i < nblk; i++) { bcache_invalidate(blk + i); } /* Write the blocks */ err = dd->dv_strategy(dd->dv_devdata, rw, blk, size, buf, rsize); /* Populate the block cache with the new data */ if (err == 0) { for (i = 0; i < nblk; i++) { bcache_insert(buf + (i * bcache_blksize),blk + i); } } return err; } /* * Handle a read request; fill in parts of the request that can * be satisfied by the cache, use the supplied strategy routine to do * device I/O and then use the I/O results to populate the cache. */ static int read_strategy(void *devdata, int unit, int rw, daddr_t blk, size_t size, char *buf, size_t *rsize) { struct bcache_devdata *dd = (struct bcache_devdata *)devdata; int p_size, result; daddr_t p_blk, i, j, nblk; caddr_t p_buf; nblk = size / bcache_blksize; result = 0; /* Satisfy any cache hits up front */ for (i = 0; i < nblk; i++) { if (bcache_lookup(buf + (bcache_blksize * i), blk + i)) { bit_set(bcache_miss, i); /* cache miss */ bcache_misses++; } else { bit_clear(bcache_miss, i); /* cache hit */ bcache_hits++; } } /* Go back and fill in any misses XXX optimise */ p_blk = -1; p_buf = NULL; p_size = 0; for (i = 0; i < nblk; i++) { if (bit_test(bcache_miss, i)) { /* miss, add to pending transfer */ if (p_blk == -1) { p_blk = blk + i; p_buf = buf + (bcache_blksize * i); p_size = 1; } else { p_size++; } } else if (p_blk != -1) { /* hit, complete pending transfer */ result = dd->dv_strategy(dd->dv_devdata, rw, p_blk, p_size * bcache_blksize, p_buf, NULL); if (result != 0) goto done; for (j = 0; j < p_size; j++) bcache_insert(p_buf + (j * bcache_blksize), p_blk + j); p_blk = -1; } } if (p_blk != -1) { /* pending transfer left */ result = dd->dv_strategy(dd->dv_devdata, rw, p_blk, p_size * bcache_blksize, p_buf, NULL); if (result != 0) goto done; for (j = 0; j < p_size; j++) bcache_insert(p_buf + (j * bcache_blksize), p_blk + j); } done: if ((result == 0) && (rsize != NULL)) *rsize = size; return(result); } /* * Requests larger than 1/2 the cache size will be bypassed and go * directly to the disk. XXX tune this. */ int bcache_strategy(void *devdata, int unit, int rw, daddr_t blk, size_t size, char *buf, size_t *rsize) { static int bcache_unit = -1; struct bcache_devdata *dd = (struct bcache_devdata *)devdata; bcache_ops++; if(bcache_unit != unit) { bcache_flush(); bcache_unit = unit; } /* bypass large requests, or when the cache is inactive */ if ((bcache_data == NULL) || ((size * 2 / bcache_blksize) > bcache_nblks)) { DEBUG("bypass %d from %d", size / bcache_blksize, blk); bcache_bypasses++; return(dd->dv_strategy(dd->dv_devdata, rw, blk, size, buf, rsize)); } switch (rw) { case F_READ: return read_strategy(devdata, unit, rw, blk, size, buf, rsize); case F_WRITE: return write_strategy(devdata, unit, rw, blk, size, buf, rsize); } return -1; } /* * Insert a block into the cache. Retire the oldest block to do so, if required. * * XXX the LRU algorithm will fail after 2^31 blocks have been transferred. */ static void bcache_insert(caddr_t buf, daddr_t blkno) { time_t now; int cand, ocount; u_int i; time(&now); cand = 0; /* assume the first block */ ocount = bcache_ctl[0].bc_count; /* find the oldest block */ for (i = 1; i < bcache_nblks; i++) { if (bcache_ctl[i].bc_blkno == blkno) { /* reuse old entry */ cand = i; break; } if (bcache_ctl[i].bc_count < ocount) { ocount = bcache_ctl[i].bc_count; cand = i; } } DEBUG("insert blk %d -> %d @ %d # %d", blkno, cand, now, bcache_bcount); bcopy(buf, bcache_data + (bcache_blksize * cand), bcache_blksize); bcache_ctl[cand].bc_blkno = blkno; bcache_ctl[cand].bc_stamp = now; bcache_ctl[cand].bc_count = bcache_bcount++; } /* * Look for a block in the cache. Blocks more than BCACHE_TIMEOUT seconds old * may be stale (removable media) and thus are discarded. Copy the block out * if successful and return zero, or return nonzero on failure. */ static int bcache_lookup(caddr_t buf, daddr_t blkno) { time_t now; u_int i; time(&now); for (i = 0; i < bcache_nblks; i++) /* cache hit? */ if ((bcache_ctl[i].bc_blkno == blkno) && ((bcache_ctl[i].bc_stamp + BCACHE_TIMEOUT) >= now)) { bcopy(bcache_data + (bcache_blksize * i), buf, bcache_blksize); DEBUG("hit blk %d <- %d (now %d then %d)", blkno, i, now, bcache_ctl[i].bc_stamp); return(0); } return(ENOENT); } /* * Invalidate a block from the cache. */ static void bcache_invalidate(daddr_t blkno) { u_int i; for (i = 0; i < bcache_nblks; i++) { if (bcache_ctl[i].bc_blkno == blkno) { bcache_ctl[i].bc_count = -1; bcache_ctl[i].bc_blkno = -1; DEBUG("invalidate blk %d", blkno); break; } } } COMMAND_SET(bcachestat, "bcachestat", "get disk block cache stats", command_bcache); static int command_bcache(int argc, char *argv[]) { u_int i; for (i = 0; i < bcache_nblks; i++) { printf("%08jx %04x %04x|", (uintmax_t)bcache_ctl[i].bc_blkno, (unsigned int)bcache_ctl[i].bc_stamp & 0xffff, bcache_ctl[i].bc_count & 0xffff); if (((i + 1) % 4) == 0) printf("\n"); } printf("\n%d ops %d bypasses %d hits %d misses %d flushes\n", bcache_ops, bcache_bypasses, bcache_hits, bcache_misses, bcache_flushes); return(CMD_OK); }