RAM Refresh
Measures the period and length of the RAM refresh window and which accesses wait for it.
| Machine | SCPH-5501 |
|---|---|
| Program | SXRAMRF and SXRAMRF2 |
This is an old revision of this page, as edited by RemmyLee at 05:11, 23 October 2026. Edit this revision | Latest revision
Overview
SXRAMRF reads root counter 1, counting system clock cycles, before and after a short access. It takes 3000 such samples back to back with interrupts off and the code in the cache. The S sample is a RAM store followed by a load of another RAM word, which waits for the store. The L sample is a RAM load and a NOP, and the N sample is two NOPs with no RAM access. The program counts how often each span occurs and records the time of every sample longer than the commonest span.1
SXRAMRF2 first repeats a load sample until one stalls, which places the code a fixed time after a refresh. It then waits k cycles, for k from 0 to 299, and takes one sample. Its samples are a store then a load (S), a load (L), two stores then a load (W), and a call into three instructions fetched from RAM through KSEG1 (F). Each kind runs its 300 delays three times, and every sample starts from a fresh synchronization.2
Results
Period
The RAM is busy once every 256 system clock cycles. Accesses that do not use RAM never wait: all 3000 N samples took 6 cycles. The S and L samples took longer when they met the refresh:1
| Sample | Span (cycles) | Samples |
|---|---|---|
| S | 16 | 2890 |
| S | 19 | 55 |
| S | 22 | 55 |
| L | 11 | 2 |
| L | 12 | 2806 |
| L | 14 | 192 |
| N | 6 | 3000 |
Length
The RAM stays busy for 6 cycles, and a load that arrives during that time waits for its end. A load placed at k 205 took 18 cycles. Each later delay up to k 210 took one cycle less, down to 13, and every other delay took 12. The three passes gave the same figures at every k.2
| Sample | Without the refresh | Longest with the refresh | Delays affected |
|---|---|---|---|
| L, a RAM load | 12 | 18 | 6 |
| S, a store then a load | 16 | 26 | 12 |
| W, two stores then a load | 18 | 28 | 14 |
| F, three uncached fetches | 22 | 28 | 18 |
Each RAM access in a sample can be held by the refresh in turn. A sample with more than one RAM access is therefore affected over more delays than a single load.2
Runs
17 October 2026 (link)
SXDEV I_MASK at init 3C040100
SXRAMRF start
SXRAMRF S span 16: 2890
SXRAMRF S span 19: 55
SXRAMRF S span 22: 55
SXRAMRF S stall 0: 46286 22
SXRAMRF S stall 7: 46551 19
SXRAMRF S stall 55: 48334 22
SXRAMRF S stall 62: 48599 19
SXRAMRF S stall 110: 50382 22
SXRAMRF S stall 117: 50647 19
SXRAMRF S stall 165: 52430 22
SXRAMRF S stall 172: 52695 19
SXRAMRF S stall 220: 54478 22
SXRAMRF S stall 227: 54743 19
SXRAMRF S stall 275: 56526 22
SXRAMRF S stall 282: 56791 19
SXRAMRF S stall 330: 58574 22
SXRAMRF S stall 337: 58839 19
SXRAMRF S stall 385: 60622 22
SXRAMRF S stall 392: 60887 19
SXRAMRF S stall 440: 62670 22
SXRAMRF S stall 447: 62935 19
SXRAMRF S stall 495: 64718 22
SXRAMRF S stall 502: 64983 19
SXRAMRF S stall 550: 66765 22
SXRAMRF S stall 557: 67030 19
SXRAMRF S stall 605: 68813 22
SXRAMRF S stall 612: 69078 19
SXRAMRF S stall 660: 70861 22
SXRAMRF S stall 667: 71126 19
SXRAMRF S stall 715: 72909 22
SXRAMRF S stall 722: 73174 19
SXRAMRF S stall 770: 74957 22
SXRAMRF S stall 777: 75222 19
SXRAMRF S stall 825: 77005 22
SXRAMRF S stall 832: 77270 19
SXRAMRF S stall 880: 79053 22
SXRAMRF S stall 887: 79318 19
SXRAMRF S stall 935: 81101 22
SXRAMRF S stall 942: 81366 19
SXRAMRF S stall 990: 83149 22
SXRAMRF S stall 997: 83414 19
SXRAMRF S stall 1045: 85197 22
SXRAMRF S stall 1052: 85462 19
SXRAMRF S stall 1100: 87245 22
SXRAMRF S stall 1107: 87510 19
SXRAMRF S stall 1155: 89293 22
SXRAMRF S stall 1162: 89558 19
SXRAMRF S stall 1210: 91341 22
SXRAMRF S stall 1217: 91606 19
SXRAMRF S stall 1265: 93389 22
SXRAMRF S stall 1272: 93654 19
SXRAMRF S stall 1320: 95437 22
SXRAMRF S stall 1327: 95702 19
SXRAMRF S stall 1375: 97485 22
SXRAMRF S stall 1382: 97750 19
SXRAMRF S stall 1430: 99533 22
SXRAMRF S stall 1437: 99798 19
SXRAMRF S stall 1485: 101581 22
SXRAMRF S stall 1492: 101846 19
SXRAMRF S stall 1540: 103629 22
SXRAMRF S stall 1547: 103894 19
SXRAMRF S stall 1595: 105677 22
SXRAMRF S stall 1602: 105942 19
SXRAMRF S stall 1650: 107725 22
SXRAMRF S stall 1657: 107990 19
SXRAMRF S stall 1705: 109773 22
SXRAMRF S stall 1712: 110038 19
SXRAMRF S stall 1760: 111821 22
SXRAMRF S stall 1767: 112086 19
SXRAMRF S stall 1815: 113869 22
SXRAMRF S stall 1822: 114134 19
SXRAMRF S stall 1870: 115917 22
SXRAMRF S stall 1877: 116182 19
SXRAMRF S stall 1925: 117965 22
SXRAMRF S stall 1932: 118230 19
SXRAMRF S stall 1980: 120013 22
SXRAMRF S stall 1987: 120278 19
SXRAMRF S stall 2035: 122061 22
SXRAMRF S stall 2042: 122326 19
SXRAMRF S stall 2090: 124109 22
SXRAMRF S stall 2097: 124374 19
SXRAMRF S stall 2145: 126157 22
SXRAMRF S stall 2152: 126422 19
SXRAMRF S stall 2200: 128205 22
SXRAMRF S stall 2207: 128470 19
SXRAMRF S stall 2255: 130253 22
SXRAMRF S stall 2262: 130518 19
SXRAMRF S stall 2310: 132300 22
SXRAMRF S stall 2317: 132565 19
SXRAMRF S stall 2365: 134348 22
SXRAMRF S stall 2372: 134613 19
SXRAMRF S stall 2420: 136396 22
SXRAMRF S stall 2427: 136661 19
SXRAMRF S stall 2475: 138444 22
SXRAMRF S stall 2482: 138709 19
SXRAMRF S stall 2530: 140492 22
SXRAMRF S stall 2537: 140757 19
SXRAMRF S stall 2585: 142540 22
SXRAMRF S stall 2592: 142805 19
SXRAMRF S stall 2640: 144588 22
SXRAMRF S stall 2647: 144853 19
SXRAMRF S stall 2695: 146636 22
SXRAMRF S stall 2702: 146901 19
SXRAMRF S stall 2750: 148684 22
SXRAMRF S stall 2757: 148949 19
SXRAMRF S stall 2805: 150732 22
SXRAMRF S stall 2812: 150997 19
SXRAMRF S stall 2860: 152780 22
SXRAMRF S stall 2867: 153045 19
SXRAMRF S stall 2915: 154828 22
SXRAMRF S stall 2922: 155093 19
SXRAMRF S stall 2970: 156876 22
SXRAMRF S stall 2977: 157141 19
SXRAMRF S samples 3000 from 46286 to 157962
SXRAMRF L span 11: 2
SXRAMRF L span 12: 2806
SXRAMRF L span 14: 192
SXRAMRF L stall 121: 35256 14
SXRAMRF L stall 136: 35768 14
SXRAMRF L stall 151: 36280 14
SXRAMRF L stall 166: 36792 14
SXRAMRF L stall 181: 37304 14
SXRAMRF L stall 196: 37816 14
SXRAMRF L stall 211: 38328 14
SXRAMRF L stall 226: 38840 14
SXRAMRF L stall 241: 39352 14
SXRAMRF L stall 256: 39864 14
SXRAMRF L stall 271: 40376 14
SXRAMRF L stall 286: 40888 14
SXRAMRF L stall 301: 41400 14
SXRAMRF L stall 316: 41912 14
SXRAMRF L stall 331: 42424 14
SXRAMRF L stall 346: 42936 14
SXRAMRF L stall 361: 43448 14
SXRAMRF L stall 376: 43960 14
SXRAMRF L stall 391: 44472 14
SXRAMRF L stall 406: 44984 14
SXRAMRF L stall 421: 45496 14
SXRAMRF L stall 436: 46008 14
SXRAMRF L stall 451: 46520 14
SXRAMRF L stall 466: 47032 14
SXRAMRF L stall 481: 47544 14
SXRAMRF L stall 496: 48056 14
SXRAMRF L stall 511: 48568 14
SXRAMRF L stall 526: 49080 14
SXRAMRF L stall 541: 49592 14
SXRAMRF L stall 556: 50104 14
SXRAMRF L stall 571: 50616 14
SXRAMRF L stall 586: 51128 14
SXRAMRF L stall 601: 51640 14
SXRAMRF L stall 616: 52152 14
SXRAMRF L stall 631: 52664 14
SXRAMRF L stall 646: 53176 14
SXRAMRF L stall 661: 53688 14
SXRAMRF L stall 676: 54200 14
SXRAMRF L stall 691: 54712 14
SXRAMRF L stall 706: 55224 14
SXRAMRF L stall 721: 55736 14
SXRAMRF L stall 736: 56248 14
SXRAMRF L stall 751: 56760 14
SXRAMRF L stall 766: 57272 14
SXRAMRF L stall 781: 57784 14
SXRAMRF L stall 796: 58296 14
SXRAMRF L stall 811: 58808 14
SXRAMRF L stall 826: 59320 14
SXRAMRF L stall 841: 59832 14
SXRAMRF L stall 856: 60344 14
SXRAMRF L stall 871: 60856 14
SXRAMRF L stall 886: 61368 14
SXRAMRF L stall 901: 61880 14
SXRAMRF L stall 916: 62392 14
SXRAMRF L stall 931: 62904 14
SXRAMRF L stall 946: 63416 14
SXRAMRF L stall 961: 63928 14
SXRAMRF L stall 976: 64440 14
SXRAMRF L stall 991: 64952 14
SXRAMRF L stall 1006: 65464 14
SXRAMRF L stall 1021: 65975 14
SXRAMRF L stall 1036: 66487 14
SXRAMRF L stall 1051: 66999 14
SXRAMRF L stall 1066: 67511 14
SXRAMRF L stall 1081: 68023 14
SXRAMRF L stall 1096: 68535 14
SXRAMRF L stall 1111: 69047 14
SXRAMRF L stall 1126: 69559 14
SXRAMRF L stall 1141: 70071 14
SXRAMRF L stall 1156: 70583 14
SXRAMRF L stall 1171: 71095 14
SXRAMRF L stall 1186: 71607 14
SXRAMRF L stall 1201: 72119 14
SXRAMRF L stall 1216: 72631 14
SXRAMRF L stall 1231: 73143 14
SXRAMRF L stall 1246: 73655 14
SXRAMRF L stall 1261: 74167 14
SXRAMRF L stall 1276: 74679 14
SXRAMRF L stall 1291: 75191 14
SXRAMRF L stall 1306: 75703 14
SXRAMRF L stall 1321: 76215 14
SXRAMRF L stall 1336: 76727 14
SXRAMRF L stall 1351: 77239 14
SXRAMRF L stall 1366: 77751 14
SXRAMRF L stall 1381: 78263 14
SXRAMRF L stall 1396: 78775 14
SXRAMRF L stall 1411: 79287 14
SXRAMRF L stall 1426: 79799 14
SXRAMRF L stall 1441: 80311 14
SXRAMRF L stall 1456: 80823 14
SXRAMRF L stall 1471: 81335 14
SXRAMRF L stall 1486: 81847 14
SXRAMRF L stall 1501: 82359 14
SXRAMRF L stall 1516: 82871 14
SXRAMRF L stall 1531: 83383 14
SXRAMRF L stall 1546: 83895 14
SXRAMRF L stall 1561: 84407 14
SXRAMRF L stall 1576: 84919 14
SXRAMRF L stall 1591: 85431 14
SXRAMRF L stall 1606: 85943 14
SXRAMRF L stall 1621: 86455 14
SXRAMRF L stall 1636: 86967 14
SXRAMRF L stall 1651: 87479 14
SXRAMRF L stall 1666: 87991 14
SXRAMRF L stall 1681: 88503 14
SXRAMRF L stall 1696: 89015 14
SXRAMRF L stall 1711: 89527 14
SXRAMRF L stall 1726: 90039 14
SXRAMRF L stall 1741: 90551 14
SXRAMRF L stall 1756: 91063 14
SXRAMRF L stall 1771: 91575 14
SXRAMRF L stall 1786: 92087 14
SXRAMRF L stall 1801: 92599 14
SXRAMRF L stall 1816: 93111 14
SXRAMRF L stall 1831: 93623 14
SXRAMRF L stall 1846: 94135 14
SXRAMRF L stall 1861: 94647 14
SXRAMRF L stall 1876: 95159 14
SXRAMRF L stall 1891: 95671 14
SXRAMRF L stall 1906: 96183 14
SXRAMRF L stall 1921: 96695 14
SXRAMRF L stall 1936: 97207 14
SXRAMRF L stall 1951: 97719 14
SXRAMRF L stall 1966: 98231 14
SXRAMRF L stall 1981: 98743 14
SXRAMRF L stall 1996: 99255 14
SXRAMRF L stall 2011: 99767 14
SXRAMRF L stall 2026: 100279 14
SXRAMRF L stall 2041: 100791 14
SXRAMRF L stall 2056: 101303 14
SXRAMRF L stall 2071: 101815 14
SXRAMRF L stall 2086: 102327 14
SXRAMRF L stall 2101: 102839 14
SXRAMRF L stall 2116: 103351 14
SXRAMRF L stall 2131: 103863 14
SXRAMRF L stall 2146: 104375 14
SXRAMRF L stall 2161: 104887 14
SXRAMRF L stall 2176: 105399 14
SXRAMRF L stall 2191: 105911 14
SXRAMRF L stall 2206: 106423 14
SXRAMRF L stall 2221: 106935 14
SXRAMRF L stall 2236: 107447 14
SXRAMRF L stall 2251: 107959 14
SXRAMRF L stall 2266: 108471 14
SXRAMRF L stall 2281: 108983 14
SXRAMRF L stall 2296: 109495 14
SXRAMRF L stall 2311: 110007 14
SXRAMRF L stall 2326: 110519 14
SXRAMRF L stall 2341: 111031 14
SXRAMRF L stall 2356: 111543 14
SXRAMRF L stall 2371: 112055 14
SXRAMRF L stall 2386: 112567 14
SXRAMRF L stall 2401: 113079 14
SXRAMRF L stall 2416: 113591 14
SXRAMRF L stall 2431: 114103 14
SXRAMRF L stall 2446: 114615 14
SXRAMRF L stall 2461: 115127 14
SXRAMRF L stall 2476: 115639 14
SXRAMRF L stall 2491: 116151 14
SXRAMRF L stall 2506: 116663 14
SXRAMRF L stall 2521: 117175 14
SXRAMRF L stall 2536: 117687 14
SXRAMRF L stall 2551: 118199 14
SXRAMRF L stall 2566: 118711 14
SXRAMRF L stall 2581: 119223 14
SXRAMRF L stall 2596: 119735 14
SXRAMRF L stall 2611: 120247 14
SXRAMRF L stall 2626: 120759 14
SXRAMRF L stall 2641: 121271 14
SXRAMRF L stall 2656: 121783 14
SXRAMRF L stall 2671: 122295 14
SXRAMRF L stall 2686: 122807 14
SXRAMRF L stall 2701: 123319 14
SXRAMRF L stall 2716: 123831 14
SXRAMRF L stall 2731: 124343 14
SXRAMRF L stall 2746: 124855 14
SXRAMRF L stall 2761: 125367 14
SXRAMRF L stall 2776: 125879 14
SXRAMRF L stall 2791: 126391 14
SXRAMRF L stall 2806: 126903 14
SXRAMRF L stall 2821: 127415 14
SXRAMRF L stall 2836: 127927 14
SXRAMRF L stall 2851: 128439 14
SXRAMRF L stall 2866: 128951 14
SXRAMRF L stall 2881: 129463 14
SXRAMRF L stall 2896: 129975 14
SXRAMRF L stall 2911: 130487 14
SXRAMRF L stall 2926: 130999 14
SXRAMRF L stall 2941: 131510 14
SXRAMRF L stall 2956: 132022 14
SXRAMRF L stall 2971: 132534 14
SXRAMRF L stall 2986: 133046 14
SXRAMRF L samples 3000 from 31139 to 133490
SXRAMRF N span 6: 3000
SXRAMRF N samples 3000 from 38442 to 122416
SXRAMRF end PASS
17 October 2026 (link)
SXDEV I_MASK at init 3C040100
SXRAMRF2 start
SXRAMRF2 sync S 0: 16 12 13
SXRAMRF2 S 0: 16*199 22*1 21*4 26*1 22*1 21*1 20*1 19*1 18*1 17*1 16*89
SXRAMRF2 sync S 1: 16 12 13
SXRAMRF2 S 1: 16*199 22*1 21*4 26*1 22*1 21*1 20*1 19*1 18*1 17*1 16*89
SXRAMRF2 sync S 2: 16 12 13
SXRAMRF2 S 2: 16*199 22*1 21*4 26*1 22*1 21*1 20*1 19*1 18*1 17*1 16*89
SXRAMRF2 sync L 0: 16 12 17
SXRAMRF2 L 0: 12*205 18*1 17*1 16*1 15*1 14*1 13*1 12*89
SXRAMRF2 sync L 1: 16 12 17
SXRAMRF2 L 1: 12*205 18*1 17*1 16*1 15*1 14*1 13*1 12*89
SXRAMRF2 sync L 2: 16 12 17
SXRAMRF2 L 2: 12*205 18*1 17*1 16*1 15*1 14*1 13*1 12*89
SXRAMRF2 sync W 0: 29 12 16
SXRAMRF2 W 0: 18*197 24*1 23*4 28*1 27*1 28*1 24*1 23*1 22*1 21*1 20*1 19*1 18*89
SXRAMRF2 sync W 1: 29 12 16
SXRAMRF2 W 1: 18*197 24*1 23*4 28*1 27*1 28*1 24*1 23*1 22*1 21*1 20*1 19*1 18*89
SXRAMRF2 sync W 2: 29 12 16
SXRAMRF2 W 2: 18*197 24*1 23*4 28*1 27*1 28*1 24*1 23*1 22*1 21*1 20*1 19*1 18*89
SXRAMRF2 sync F 0: 42 12 17
SXRAMRF2 F 0: 22*195 28*1 27*1 26*4 28*1 27*1 26*4 28*1 27*1 26*1 25*1 24*1 23*1 22*87
SXRAMRF2 sync F 1: 42 12 17
SXRAMRF2 F 1: 22*195 28*1 27*1 26*4 28*1 27*1 26*4 28*1 27*1 26*1 25*1 24*1 23*1 22*87
SXRAMRF2 sync F 2: 42 12 17
SXRAMRF2 F 2: 22*34 21*1 22*160 28*1 27*1 26*4 28*1 27*1 26*4 28*1 27*1 26*1 25*1 24*1 23*1 22*83 21*1 22*3
SXRAMRF2 end PASS
References
-
^ a b Hardware test run 20261017T0103Z-5501a-link on the SCPH-5501: SXRAMRF.txt.
-
^ a b c Hardware test run 20261017T0108Z-5501a-link on the SCPH-5501: SXRAMRF2.txt.
Categories: Hardware tests