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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
64 lines
2.2 KiB
C
64 lines
2.2 KiB
C
/*-
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* Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
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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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/*
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* Obtain memory configuration information from the BIOS
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*/
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#include <stand.h>
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#include "libi386.h"
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#include "btxv86.h"
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vm_offset_t memtop, memtop_copyin, high_heap_base;
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uint32_t bios_basemem, bios_extmem, high_heap_size;
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/*
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* The minimum amount of memory to reserve in bios_extmem for the heap.
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*/
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#define HEAP_MIN (64 * 1024 * 1024)
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void
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bios_getmem(void)
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{
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bios_basemem = ((*(u_char *)PTOV(0xA1501) & 0x07) + 1) * 128 * 1024;
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bios_extmem = *(u_char *)PTOV(0xA1401) * 128 * 1024 +
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*(u_int16_t *)PTOV(0xA1594) * 1024 * 1024;
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/* Set memtop to actual top of memory */
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memtop = memtop_copyin = 0x100000 + bios_extmem;
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/*
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* If we have extended memory, use the last 3MB of 'extended' memory
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* as a high heap candidate.
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*/
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if (bios_extmem >= HEAP_MIN) {
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high_heap_size = HEAP_MIN;
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high_heap_base = memtop - HEAP_MIN;
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}
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}
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