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@@ -0,0 +1,68 @@
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+#include <u.h>
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+#include <libc.h>
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+
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+int nring = 32;
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+int niter = 65536;
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+int debug = 0;
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+char data[8192];
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+int i;
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+int id;
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+int intr = 0;
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+
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+void
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+handler(void *v, char *s)
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+{
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+ print("%d: %d iterations\n", id, i);
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+ if (intr++ < 16)
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+ noted(NCONT);
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+ exits("too many interrupts");
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+}
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+
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+void
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+main(int argc, char *argv[])
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+{
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+ int pid;
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+
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+ if (notify(handler)){
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+ sysfatal("notify: %r");
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+ }
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+
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+ if (argc > 1)
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+ nring = strtoull(argv[1], 0, 0);
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+
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+ if (argc > 2)
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+ niter = strtoull(argv[2], 0, 0);
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+ debug = argc > 3;
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+
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+ print("Running with %d pipes %d times\n", nring, niter);
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+ int *pfd = malloc(sizeof(*pipe)* nring * 2);
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+
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+ if (pfd == nil)
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+ sysfatal(smprint("alloc %d pipes: %r", nring*2));
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+
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+ for(i = 0; i < nring; i++)
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+ if (pipe(&pfd[i*2]) < 0)
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+ sysfatal(smprint("create pipe pair %d of %d: %r", i, nring));
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+
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+ for(i = 0; debug && i < nring; i++ ) print("pfd[%d,%d]\n", pfd[i*2],pfd[i*2+1]);
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+ for(i = 0, id = 0; i < nring-1; i++, id++) {
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+ pid = fork();
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+ if (pid == 0)
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+ break;
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+ if (pid < 0)
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+ sysfatal("fork");
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+ }
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+
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+ if (debug) print("Forked. pid %d\n", getpid());
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+ for(i = 0; debug && i < nring; i++ ) print("pfd[%d,%d]\n", pfd[i*2],pfd[i*2+1]);
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+ for(i = 0; i < niter; i++) {
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+ if (debug) print("%d: write %d\n", id, pfd[(id%nring)*2+1]);
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+ int amt = write(pfd[(id%nring)*2+1], data, sizeof(data));
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+ if (amt < sizeof(data))
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+ sysfatal(smprint("%d: write only got %d of %d: %r", id, amt, sizeof(data)));
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+ if (debug) print("%d: read %d\n", id, pfd[(id%nring)*2]);
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+ amt = read(pfd[(id%nring)*2], data, sizeof(data));
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+ if (amt < sizeof(data))
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+ sysfatal(smprint("%d: read only got %d of %d: %r", id, amt, sizeof(data)));
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+ }
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+}
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