60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
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#define _SYSTEM
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#include <minix/libminixfs.h>
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#include <minix/dmap.h>
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#include <minix/u64.h>
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#include <sys/param.h>
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#include <errno.h>
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u32_t fs_bufs_heuristic(int minbufs, u32_t btotal, u32_t bfree,
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int blocksize, dev_t majordev)
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{
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struct vm_stats_info vsi;
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int bufs;
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u32_t kbytes_used_fs, kbytes_total_fs, kbcache, kb_fsmax;
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u32_t kbytes_remain_mem, bused;
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bused = btotal-bfree;
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/* but we simply need minbufs no matter what, and we don't
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* want more than that if we're a memory device
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*/
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if(majordev == MEMORY_MAJOR) {
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return minbufs;
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}
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/* set a reasonable cache size; cache at most a certain
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* portion of the used FS, and at most a certain %age of remaining
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* memory
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*/
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if((vm_info_stats(&vsi) != OK)) {
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bufs = 1024;
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printf("fslib: heuristic info fail: default to %d bufs\n", bufs);
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return bufs;
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}
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kbytes_remain_mem = div64u(mul64u(vsi.vsi_free, vsi.vsi_pagesize), 1024);
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/* check fs usage. */
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kbytes_used_fs = div64u(mul64u(bused, blocksize), 1024);
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kbytes_total_fs = div64u(mul64u(btotal, blocksize), 1024);
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/* heuristic for a desired cache size based on FS usage;
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* but never bigger than half of the total filesystem
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*/
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kb_fsmax = sqrt_approx(kbytes_used_fs)*40;
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kb_fsmax = MIN(kb_fsmax, kbytes_total_fs/2);
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/* heuristic for a maximum usage - 10% of remaining memory */
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kbcache = MIN(kbytes_remain_mem/10, kb_fsmax);
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bufs = kbcache * 1024 / blocksize;
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/* but we simply need MINBUFS no matter what */
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if(bufs < minbufs)
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bufs = minbufs;
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return bufs;
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}
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