mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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6549a8c0c3
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array
member[1][2], introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by this
change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293
("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gustavo A. R. Silva <gustavo@embeddedor.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200515172926.GA31976@embeddedor
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
330 lines
7.0 KiB
C
330 lines
7.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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*
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* sched-messaging.c
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*
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* messaging: Benchmark for scheduler and IPC mechanisms
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*
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* Based on hackbench by Rusty Russell <rusty@rustcorp.com.au>
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* Ported to perf by Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
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*
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*/
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#include <subcmd/parse-options.h>
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#include "bench.h"
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/* Test groups of 20 processes spraying to 20 receivers */
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <sys/wait.h>
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#include <sys/time.h>
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#include <poll.h>
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#include <limits.h>
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#include <err.h>
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#include <linux/time64.h>
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#define DATASIZE 100
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static bool use_pipes = false;
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static unsigned int nr_loops = 100;
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static bool thread_mode = false;
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static unsigned int num_groups = 10;
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struct sender_context {
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unsigned int num_fds;
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int ready_out;
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int wakefd;
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int out_fds[];
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};
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struct receiver_context {
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unsigned int num_packets;
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int in_fds[2];
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int ready_out;
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int wakefd;
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};
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static void fdpair(int fds[2])
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{
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if (use_pipes) {
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if (pipe(fds) == 0)
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return;
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} else {
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if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds) == 0)
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return;
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}
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err(EXIT_FAILURE, use_pipes ? "pipe()" : "socketpair()");
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}
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/* Block until we're ready to go */
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static void ready(int ready_out, int wakefd)
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{
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char dummy;
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struct pollfd pollfd = { .fd = wakefd, .events = POLLIN };
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/* Tell them we're ready. */
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if (write(ready_out, &dummy, 1) != 1)
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err(EXIT_FAILURE, "CLIENT: ready write");
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/* Wait for "GO" signal */
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if (poll(&pollfd, 1, -1) != 1)
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err(EXIT_FAILURE, "poll");
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}
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/* Sender sprays nr_loops messages down each file descriptor */
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static void *sender(struct sender_context *ctx)
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{
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char data[DATASIZE];
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unsigned int i, j;
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ready(ctx->ready_out, ctx->wakefd);
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/* Now pump to every receiver. */
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for (i = 0; i < nr_loops; i++) {
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for (j = 0; j < ctx->num_fds; j++) {
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int ret, done = 0;
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again:
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ret = write(ctx->out_fds[j], data + done,
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sizeof(data)-done);
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if (ret < 0)
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err(EXIT_FAILURE, "SENDER: write");
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done += ret;
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if (done < DATASIZE)
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goto again;
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}
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}
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return NULL;
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}
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/* One receiver per fd */
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static void *receiver(struct receiver_context* ctx)
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{
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unsigned int i;
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if (!thread_mode)
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close(ctx->in_fds[1]);
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/* Wait for start... */
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ready(ctx->ready_out, ctx->wakefd);
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/* Receive them all */
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for (i = 0; i < ctx->num_packets; i++) {
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char data[DATASIZE];
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int ret, done = 0;
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again:
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ret = read(ctx->in_fds[0], data + done, DATASIZE - done);
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if (ret < 0)
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err(EXIT_FAILURE, "SERVER: read");
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done += ret;
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if (done < DATASIZE)
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goto again;
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}
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return NULL;
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}
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static pthread_t create_worker(void *ctx, void *(*func)(void *))
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{
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pthread_attr_t attr;
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pthread_t childid;
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int ret;
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if (!thread_mode) {
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/* process mode */
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/* Fork the receiver. */
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switch (fork()) {
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case -1:
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err(EXIT_FAILURE, "fork()");
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break;
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case 0:
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(*func) (ctx);
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exit(0);
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break;
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default:
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break;
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}
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return (pthread_t)0;
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}
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if (pthread_attr_init(&attr) != 0)
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err(EXIT_FAILURE, "pthread_attr_init:");
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#ifndef __ia64__
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if (pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN) != 0)
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err(EXIT_FAILURE, "pthread_attr_setstacksize");
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#endif
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ret = pthread_create(&childid, &attr, func, ctx);
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if (ret != 0)
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err(EXIT_FAILURE, "pthread_create failed");
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return childid;
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}
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static void reap_worker(pthread_t id)
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{
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int proc_status;
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void *thread_status;
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if (!thread_mode) {
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/* process mode */
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wait(&proc_status);
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if (!WIFEXITED(proc_status))
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exit(1);
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} else {
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pthread_join(id, &thread_status);
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}
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}
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/* One group of senders and receivers */
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static unsigned int group(pthread_t *pth,
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unsigned int num_fds,
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int ready_out,
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int wakefd)
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{
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unsigned int i;
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struct sender_context *snd_ctx = malloc(sizeof(struct sender_context)
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+ num_fds * sizeof(int));
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if (!snd_ctx)
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err(EXIT_FAILURE, "malloc()");
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for (i = 0; i < num_fds; i++) {
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int fds[2];
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struct receiver_context *ctx = malloc(sizeof(*ctx));
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if (!ctx)
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err(EXIT_FAILURE, "malloc()");
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/* Create the pipe between client and server */
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fdpair(fds);
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ctx->num_packets = num_fds * nr_loops;
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ctx->in_fds[0] = fds[0];
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ctx->in_fds[1] = fds[1];
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ctx->ready_out = ready_out;
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ctx->wakefd = wakefd;
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pth[i] = create_worker(ctx, (void *)receiver);
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snd_ctx->out_fds[i] = fds[1];
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if (!thread_mode)
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close(fds[0]);
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}
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/* Now we have all the fds, fork the senders */
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for (i = 0; i < num_fds; i++) {
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snd_ctx->ready_out = ready_out;
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snd_ctx->wakefd = wakefd;
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snd_ctx->num_fds = num_fds;
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pth[num_fds+i] = create_worker(snd_ctx, (void *)sender);
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}
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/* Close the fds we have left */
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if (!thread_mode)
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for (i = 0; i < num_fds; i++)
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close(snd_ctx->out_fds[i]);
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/* Return number of children to reap */
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return num_fds * 2;
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}
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static const struct option options[] = {
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OPT_BOOLEAN('p', "pipe", &use_pipes,
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"Use pipe() instead of socketpair()"),
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OPT_BOOLEAN('t', "thread", &thread_mode,
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"Be multi thread instead of multi process"),
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OPT_UINTEGER('g', "group", &num_groups, "Specify number of groups"),
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OPT_UINTEGER('l', "nr_loops", &nr_loops, "Specify the number of loops to run (default: 100)"),
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OPT_END()
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};
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static const char * const bench_sched_message_usage[] = {
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"perf bench sched messaging <options>",
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NULL
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};
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int bench_sched_messaging(int argc, const char **argv)
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{
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unsigned int i, total_children;
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struct timeval start, stop, diff;
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unsigned int num_fds = 20;
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int readyfds[2], wakefds[2];
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char dummy;
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pthread_t *pth_tab;
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argc = parse_options(argc, argv, options,
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bench_sched_message_usage, 0);
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pth_tab = malloc(num_fds * 2 * num_groups * sizeof(pthread_t));
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if (!pth_tab)
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err(EXIT_FAILURE, "main:malloc()");
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fdpair(readyfds);
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fdpair(wakefds);
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total_children = 0;
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for (i = 0; i < num_groups; i++)
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total_children += group(pth_tab+total_children, num_fds,
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readyfds[1], wakefds[0]);
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/* Wait for everyone to be ready */
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for (i = 0; i < total_children; i++)
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if (read(readyfds[0], &dummy, 1) != 1)
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err(EXIT_FAILURE, "Reading for readyfds");
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gettimeofday(&start, NULL);
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/* Kick them off */
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if (write(wakefds[1], &dummy, 1) != 1)
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err(EXIT_FAILURE, "Writing to start them");
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/* Reap them all */
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for (i = 0; i < total_children; i++)
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reap_worker(pth_tab[i]);
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gettimeofday(&stop, NULL);
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timersub(&stop, &start, &diff);
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switch (bench_format) {
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case BENCH_FORMAT_DEFAULT:
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printf("# %d sender and receiver %s per group\n",
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num_fds, thread_mode ? "threads" : "processes");
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printf("# %d groups == %d %s run\n\n",
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num_groups, num_groups * 2 * num_fds,
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thread_mode ? "threads" : "processes");
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printf(" %14s: %lu.%03lu [sec]\n", "Total time",
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diff.tv_sec,
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(unsigned long) (diff.tv_usec / USEC_PER_MSEC));
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break;
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case BENCH_FORMAT_SIMPLE:
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printf("%lu.%03lu\n", diff.tv_sec,
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(unsigned long) (diff.tv_usec / USEC_PER_MSEC));
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break;
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default:
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/* reaching here is something disaster */
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fprintf(stderr, "Unknown format:%d\n", bench_format);
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exit(1);
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break;
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}
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free(pth_tab);
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return 0;
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}
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