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authorChris Metcalf <cmetcalf@tilera.com>2011-02-28 15:48:39 -0500
committerChris Metcalf <cmetcalf@tilera.com>2011-03-01 16:21:06 -0500
commit63b7ca6b04427aea9075d6f5f5f15b82e115bce4 (patch)
tree97a72ec3d243a46475e880b2c5703a167165f961 /arch/tile/lib/cacheflush.c
parent3cebbafd28e6f91677f3becffcdf9150b74a4e0c (diff)
arch/tile: enhance existing finv_buffer_remote() routine
It now takes an additional argument so it can be used to flush-and-invalidate pages that are cached using hash-for-home as well those that are cached with coherence point on a single cpu. This allows it to be used more widely for changing the coherence point of arbitrary pages when necessary. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Diffstat (limited to 'arch/tile/lib/cacheflush.c')
-rw-r--r--arch/tile/lib/cacheflush.c102
1 files changed, 102 insertions, 0 deletions
diff --git a/arch/tile/lib/cacheflush.c b/arch/tile/lib/cacheflush.c
index 11b6164c2097..35c1d8ca5f38 100644
--- a/arch/tile/lib/cacheflush.c
+++ b/arch/tile/lib/cacheflush.c
@@ -21,3 +21,105 @@ void __flush_icache_range(unsigned long start, unsigned long end)
21{ 21{
22 invalidate_icache((const void *)start, end - start, PAGE_SIZE); 22 invalidate_icache((const void *)start, end - start, PAGE_SIZE);
23} 23}
24
25
26/* Force a load instruction to issue. */
27static inline void force_load(char *p)
28{
29 *(volatile char *)p;
30}
31
32/*
33 * Flush and invalidate a VA range that is homed remotely on a single
34 * core (if "!hfh") or homed via hash-for-home (if "hfh"), waiting
35 * until the memory controller holds the flushed values.
36 */
37void finv_buffer_remote(void *buffer, size_t size, int hfh)
38{
39 char *p, *base;
40 size_t step_size, load_count;
41 const unsigned long STRIPE_WIDTH = 8192;
42
43 /*
44 * Flush and invalidate the buffer out of the local L1/L2
45 * and request the home cache to flush and invalidate as well.
46 */
47 __finv_buffer(buffer, size);
48
49 /*
50 * Wait for the home cache to acknowledge that it has processed
51 * all the flush-and-invalidate requests. This does not mean
52 * that the flushed data has reached the memory controller yet,
53 * but it does mean the home cache is processing the flushes.
54 */
55 __insn_mf();
56
57 /*
58 * Issue a load to the last cache line, which can't complete
59 * until all the previously-issued flushes to the same memory
60 * controller have also completed. If we weren't striping
61 * memory, that one load would be sufficient, but since we may
62 * be, we also need to back up to the last load issued to
63 * another memory controller, which would be the point where
64 * we crossed an 8KB boundary (the granularity of striping
65 * across memory controllers). Keep backing up and doing this
66 * until we are before the beginning of the buffer, or have
67 * hit all the controllers.
68 *
69 * If we are flushing a hash-for-home buffer, it's even worse.
70 * Each line may be homed on a different tile, and each tile
71 * may have up to four lines that are on different
72 * controllers. So as we walk backwards, we have to touch
73 * enough cache lines to satisfy these constraints. In
74 * practice this ends up being close enough to "load from
75 * every cache line on a full memory stripe on each
76 * controller" that we simply do that, to simplify the logic.
77 *
78 * FIXME: See bug 9535 for some issues with this code.
79 */
80 if (hfh) {
81 step_size = L2_CACHE_BYTES;
82 load_count = (STRIPE_WIDTH / L2_CACHE_BYTES) *
83 (1 << CHIP_LOG_NUM_MSHIMS());
84 } else {
85 step_size = STRIPE_WIDTH;
86 load_count = (1 << CHIP_LOG_NUM_MSHIMS());
87 }
88
89 /* Load the last byte of the buffer. */
90 p = (char *)buffer + size - 1;
91 force_load(p);
92
93 /* Bump down to the end of the previous stripe or cache line. */
94 p -= step_size;
95 p = (char *)((unsigned long)p | (step_size - 1));
96
97 /* Figure out how far back we need to go. */
98 base = p - (step_size * (load_count - 2));
99 if ((long)base < (long)buffer)
100 base = buffer;
101
102 /*
103 * Fire all the loads we need. The MAF only has eight entries
104 * so we can have at most eight outstanding loads, so we
105 * unroll by that amount.
106 */
107#pragma unroll 8
108 for (; p >= base; p -= step_size)
109 force_load(p);
110
111 /*
112 * Repeat, but with inv's instead of loads, to get rid of the
113 * data we just loaded into our own cache and the old home L3.
114 * No need to unroll since inv's don't target a register.
115 */
116 p = (char *)buffer + size - 1;
117 __insn_inv(p);
118 p -= step_size;
119 p = (char *)((unsigned long)p | (step_size - 1));
120 for (; p >= base; p -= step_size)
121 __insn_inv(p);
122
123 /* Wait for the load+inv's (and thus finvs) to have completed. */
124 __insn_mf();
125}