procrank/procrank.c - platform/system/extras - Git at Google

 /*
  * Copyright (C) 2008 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
 #include <unistd.h>

 #include <pagemap/pagemap.h>

 struct proc_info {
     pid_t pid;
     pm_memusage_t usage;
     uint64_t wss;
 };

 static void usage(char *myname);
 static int getprocname(pid_t pid, char *buf, int len);
 static int numcmp(uint64_t a, uint64_t b);

 #define declare_sort(field) \
     static int sort_by_ ## field (const void *a, const void *b)

 declare_sort(vss);
 declare_sort(rss);
 declare_sort(pss);
 declare_sort(uss);
 declare_sort(swap);

 int (*compfn)(const void *a, const void *b);
 static int order;

 void print_mem_info() {
     char buffer[1024];
     int numFound = 0;

     int fd = open("/proc/meminfo", O_RDONLY);

     if (fd < 0) {
         printf("Unable to open /proc/meminfo: %s\n", strerror(errno));
         return;
     }

     const int len = read(fd, buffer, sizeof(buffer)-1);
     close(fd);

     if (len < 0) {
         printf("Empty /proc/meminfo");
         return;
     }
     buffer[len] = 0;

     static const char* const tags[] = {
             "MemTotal:",
             "MemFree:",
             "Buffers:",
             "Cached:",
             "Shmem:",
             "Slab:",
             NULL
     };
     static const int tagsLen[] = {
             9,
             8,
             8,
             7,
             6,
             5,
             0
     };
     uint64_t mem[] = { 0, 0, 0, 0, 0, 0 };

     char* p = buffer;
     while (*p && numFound < 6) {
         int i = 0;
         while (tags[i]) {
             if (strncmp(p, tags[i], tagsLen[i]) == 0) {
                 p += tagsLen[i];
                 while (*p == ' ') p++;
                 char* num = p;
                 while (*p >= '0' && *p <= '9') p++;
                 if (*p != 0) {
                     *p = 0;
                     p++;
                 }
                 mem[i] = atoll(num);
                 numFound++;
                 break;
             }
             i++;
         }
         while (*p && *p != '\n') {
             p++;
         }
         if (*p) p++;
     }

     printf("RAM: %" PRIu64 "K total, %" PRIu64 "K free, %" PRIu64 "K buffers, "
             "%" PRIu64 "K cached, %" PRIu64 "K shmem, %" PRIu64 "K slab\n",
             mem[0], mem[1], mem[2], mem[3], mem[4], mem[5]);
 }

 int main(int argc, char *argv[]) {
     pm_kernel_t *ker;
     pm_process_t *proc;
     pid_t *pids;
     struct proc_info **procs;
     size_t num_procs;
     uint64_t total_pss;
     uint64_t total_uss;
     uint64_t total_swap;
     char cmdline[256]; // this must be within the range of int
     int error;
     bool has_swap = false;
     uint64_t required_flags = 0;
     uint64_t flags_mask = 0;

     #define WS_OFF   0
     #define WS_ONLY  1
     #define WS_RESET 2
     int ws;

     int arg;
     size_t i, j;

     signal(SIGPIPE, SIG_IGN);
     compfn = &sort_by_pss;
     order = -1;
     ws = WS_OFF;

     for (arg = 1; arg < argc; arg++) {
         if (!strcmp(argv[arg], "-v")) { compfn = &sort_by_vss; continue; }
         if (!strcmp(argv[arg], "-r")) { compfn = &sort_by_rss; continue; }
         if (!strcmp(argv[arg], "-p")) { compfn = &sort_by_pss; continue; }
         if (!strcmp(argv[arg], "-u")) { compfn = &sort_by_uss; continue; }
         if (!strcmp(argv[arg], "-s")) { compfn = &sort_by_swap; continue; }
         if (!strcmp(argv[arg], "-c")) { required_flags = 0; flags_mask = PM_PAGE_SWAPBACKED; continue; }
         if (!strcmp(argv[arg], "-C")) { required_flags = flags_mask = PM_PAGE_SWAPBACKED; continue; }
         if (!strcmp(argv[arg], "-k")) { required_flags = flags_mask = PM_PAGE_KSM; continue; }
         if (!strcmp(argv[arg], "-w")) { ws = WS_ONLY; continue; }
         if (!strcmp(argv[arg], "-W")) { ws = WS_RESET; continue; }
         if (!strcmp(argv[arg], "-R")) { order *= -1; continue; }
         if (!strcmp(argv[arg], "-h")) { usage(argv[0]); exit(0); }
         fprintf(stderr, "Invalid argument \"%s\".\n", argv[arg]);
         usage(argv[0]);
         exit(EXIT_FAILURE);
     }

     error = pm_kernel_create(&ker);
     if (error) {
         fprintf(stderr, "Error creating kernel interface -- "
                         "does this kernel have pagemap?\n");
         exit(EXIT_FAILURE);
     }

     error = pm_kernel_pids(ker, &pids, &num_procs);
     if (error) {
         fprintf(stderr, "Error listing processes.\n");
         exit(EXIT_FAILURE);
     }

     procs = calloc(num_procs, sizeof(struct proc_info*));
     if (procs == NULL) {
         fprintf(stderr, "calloc: %s", strerror(errno));
         exit(EXIT_FAILURE);
     }

     for (i = 0; i < num_procs; i++) {
         procs[i] = malloc(sizeof(struct proc_info));
         if (procs[i] == NULL) {
             fprintf(stderr, "malloc: %s\n", strerror(errno));
             exit(EXIT_FAILURE);
         }
         procs[i]->pid = pids[i];
         pm_memusage_zero(&procs[i]->usage);
         error = pm_process_create(ker, pids[i], &proc);
         if (error) {
             fprintf(stderr, "warning: could not create process interface for %d\n", pids[i]);
             continue;
         }

         switch (ws) {
         case WS_OFF:
             error = pm_process_usage_flags(proc, &procs[i]->usage, flags_mask,
                                            required_flags);
             break;
         case WS_ONLY:
             error = pm_process_workingset(proc, &procs[i]->usage, 0);
             break;
         case WS_RESET:
             error = pm_process_workingset(proc, NULL, 1);
             break;
         }

         if (error) {
             fprintf(stderr, "warning: could not read usage for %d\n", pids[i]);
         }

         if (ws != WS_RESET && procs[i]->usage.swap) {
             has_swap = true;
         }

         pm_process_destroy(proc);
     }

     free(pids);

     if (ws == WS_RESET) exit(0);

     j = 0;
     for (i = 0; i < num_procs; i++) {
         if (procs[i]->usage.vss) {
             procs[j++] = procs[i];
         } else {
             free(procs[i]);
         }
     }
     num_procs = j;

     qsort(procs, num_procs, sizeof(procs[0]), compfn);

     printf("%5s  ", "PID");
     if (ws) {
         printf("%s  %7s  %7s  ", "WRss", "WPss", "WUss");
         if (has_swap) {
             printf("%7s  ", "WSwap");
         }
     } else {
         printf("%8s  %7s  %7s  %7s  ", "Vss", "Rss", "Pss", "Uss");
         if (has_swap) {
             printf("%7s  ", "Swap");
         }
     }

     printf("%s\n", "cmdline");

     total_pss = 0;
     total_uss = 0;
     total_swap = 0;

     for (i = 0; i < num_procs; i++) {
         if (getprocname(procs[i]->pid, cmdline, (int)sizeof(cmdline)) < 0) {
             /*
              * Something is probably seriously wrong if writing to the stack
              * failed.
              */
             free(procs[i]);
             continue;
         }

         total_pss += procs[i]->usage.pss;
         total_uss += procs[i]->usage.uss;
         total_swap += procs[i]->usage.swap;

         printf("%5d  ", procs[i]->pid);

         if (ws) {
             printf("%6zuK  %6zuK  %6zuK  ",
                 procs[i]->usage.rss / 1024,
                 procs[i]->usage.pss / 1024,
                 procs[i]->usage.uss / 1024
             );
         } else {
             printf("%7zuK  %6zuK  %6zuK  %6zuK  ",
                 procs[i]->usage.vss / 1024,
                 procs[i]->usage.rss / 1024,
                 procs[i]->usage.pss / 1024,
                 procs[i]->usage.uss / 1024
             );
         }

         if (has_swap) {
             printf("%6zuK  ", procs[i]->usage.swap / 1024);
         }

         printf("%s\n", cmdline);

         free(procs[i]);
     }

     free(procs);

     /* Print the separator line */
     printf("%5s  ", "");

     if (ws) {
         printf("%7s  %7s  %7s  ", "", "------", "------");
     } else {
         printf("%8s  %7s  %7s  %7s  ", "", "", "------", "------");
     }

     if (has_swap) {
         printf("%7s  ", "------");
     }

     printf("%s\n", "------");

     /* Print the total line */
     printf("%5s  ", "");
     if (ws) {
         printf("%7s  %6" PRIu64 "K  %" PRIu64 "K  ",
             "", total_pss / 1024, total_uss / 1024);
     } else {
         printf("%8s  %7s  %6" PRIu64 "K  %6" PRIu64 "K  ",
             "", "", total_pss / 1024, total_uss / 1024);
     }

     if (has_swap) {
         printf("%6" PRIu64 "K  ", total_swap / 1024);
     }

     printf("TOTAL\n");

     printf("\n");
     print_mem_info();

     return 0;
 }

 static void usage(char *myname) {
     fprintf(stderr, "Usage: %s [ -W ] [ -v | -r | -p | -u | -s | -h ]\n"
                     "    -v  Sort by VSS.\n"
                     "    -r  Sort by RSS.\n"
                     "    -p  Sort by PSS.\n"
                     "    -u  Sort by USS.\n"
                     "    -s  Sort by swap.\n"
                     "        (Default sort order is PSS.)\n"
                     "    -R  Reverse sort order (default is descending).\n"
                     "    -c  Only show cached (storage backed) pages\n"
                     "    -C  Only show non-cached (ram/swap backed) pages\n"
                     "    -k  Only show pages collapsed by KSM\n"
                     "    -w  Display statistics for working set only.\n"
                     "    -W  Reset working set of all processes.\n"
                     "    -h  Display this help screen.\n",
     myname);
 }

 /*
  * Get the process name for a given PID. Inserts the process name into buffer
  * buf of length len. The size of the buffer must be greater than zero to get
  * any useful output.
  *
  * Note that fgets(3) only declares length as an int, so our buffer size is
  * also declared as an int.
  *
  * Returns 0 on success, a positive value on partial success, and -1 on
  * failure. Other interesting values:
  *   1 on failure to create string to examine proc cmdline entry
  *   2 on failure to open proc cmdline entry
  *   3 on failure to read proc cmdline entry
  */
 static int getprocname(pid_t pid, char *buf, int len) {
     char *filename;
     FILE *f;
     int rc = 0;
     static const char* unknown_cmdline = "<unknown>";

     if (len <= 0) {
         return -1;
     }

     if (asprintf(&filename, "/proc/%d/cmdline", pid) < 0) {
         rc = 1;
         goto exit;
     }

     f = fopen(filename, "r");
     if (f == NULL) {
         rc = 2;
         goto releasefilename;
     }

     if (fgets(buf, len, f) == NULL) {
         rc = 3;
         goto closefile;
     }

 closefile:
     (void) fclose(f);
 releasefilename:
     free(filename);
 exit:
     if (rc != 0) {
         /*
          * The process went away before we could read its process name. Try
          * to give the user "<unknown>" here, but otherwise they get to look
          * at a blank.
          */
         if (strlcpy(buf, unknown_cmdline, (size_t)len) >= (size_t)len) {
             rc = 4;
         }
     }

     return rc;
 }

 static int numcmp(uint64_t a, uint64_t b) {
     if (a < b) return -1;
     if (a > b) return 1;
     return 0;
 }

 #define create_sort(field, compfn) \
     static int sort_by_ ## field (const void *a, const void *b) { \
         return order * compfn( \
             (*((struct proc_info**)a))->usage.field, \
             (*((struct proc_info**)b))->usage.field \
         ); \
     }

 create_sort(vss, numcmp)
 create_sort(rss, numcmp)
 create_sort(pss, numcmp)
 create_sort(uss, numcmp)
 create_sort(swap, numcmp)
	/*
	* Copyright (C) 2008 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include <dirent.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <inttypes.h>
	#include <stdbool.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/types.h>
	#include <unistd.h>

	#include <pagemap/pagemap.h>

	struct proc_info {
	pid_t pid;
	pm_memusage_t usage;
	uint64_t wss;
	};

	static void usage(char *myname);
	static int getprocname(pid_t pid, char *buf, int len);
	static int numcmp(uint64_t a, uint64_t b);

	#define declare_sort(field) \
	static int sort_by_ ## field (const void a, const void b)

	declare_sort(vss);
	declare_sort(rss);
	declare_sort(pss);
	declare_sort(uss);
	declare_sort(swap);

	int (compfn)(const void a, const void *b);
	static int order;

	void print_mem_info() {
	char buffer[1024];
	int numFound = 0;

	int fd = open("/proc/meminfo", O_RDONLY);

	if (fd < 0) {
	printf("Unable to open /proc/meminfo: %s\n", strerror(errno));
	return;
	}

	const int len = read(fd, buffer, sizeof(buffer)-1);
	close(fd);

	if (len < 0) {
	printf("Empty /proc/meminfo");
	return;
	}
	buffer[len] = 0;

	static const char* const tags[] = {
	"MemTotal:",
	"MemFree:",
	"Buffers:",
	"Cached:",
	"Shmem:",
	"Slab:",
	NULL
	};
	static const int tagsLen[] = {
	9,
	8,
	8,
	7,
	6,
	5,
	0
	};
	uint64_t mem[] = { 0, 0, 0, 0, 0, 0 };

	char* p = buffer;
	while (*p && numFound < 6) {
	int i = 0;
	while (tags[i]) {
	if (strncmp(p, tags[i], tagsLen[i]) == 0) {
	p += tagsLen[i];
	while (*p == ' ') p++;
	char* num = p;
	while (p >= '0' && p <= '9') p++;
	if (*p != 0) {
	*p = 0;
	p++;
	}
	mem[i] = atoll(num);
	numFound++;
	break;
	}
	i++;
	}
	while (p && p != '\n') {
	p++;
	}
	if (*p) p++;
	}

	printf("RAM: %" PRIu64 "K total, %" PRIu64 "K free, %" PRIu64 "K buffers, "
	"%" PRIu64 "K cached, %" PRIu64 "K shmem, %" PRIu64 "K slab\n",
	mem[0], mem[1], mem[2], mem[3], mem[4], mem[5]);
	}

	int main(int argc, char *argv[]) {
	pm_kernel_t *ker;
	pm_process_t *proc;
	pid_t *pids;
	struct proc_info **procs;
	size_t num_procs;
	uint64_t total_pss;
	uint64_t total_uss;
	uint64_t total_swap;
	char cmdline[256]; // this must be within the range of int
	int error;
	bool has_swap = false;
	uint64_t required_flags = 0;
	uint64_t flags_mask = 0;

	#define WS_OFF 0
	#define WS_ONLY 1
	#define WS_RESET 2
	int ws;

	int arg;
	size_t i, j;

	signal(SIGPIPE, SIG_IGN);
	compfn = &sort_by_pss;
	order = -1;
	ws = WS_OFF;

	for (arg = 1; arg < argc; arg++) {
	if (!strcmp(argv[arg], "-v")) { compfn = &sort_by_vss; continue; }
	if (!strcmp(argv[arg], "-r")) { compfn = &sort_by_rss; continue; }
	if (!strcmp(argv[arg], "-p")) { compfn = &sort_by_pss; continue; }
	if (!strcmp(argv[arg], "-u")) { compfn = &sort_by_uss; continue; }
	if (!strcmp(argv[arg], "-s")) { compfn = &sort_by_swap; continue; }
	if (!strcmp(argv[arg], "-c")) { required_flags = 0; flags_mask = PM_PAGE_SWAPBACKED; continue; }
	if (!strcmp(argv[arg], "-C")) { required_flags = flags_mask = PM_PAGE_SWAPBACKED; continue; }
	if (!strcmp(argv[arg], "-k")) { required_flags = flags_mask = PM_PAGE_KSM; continue; }
	if (!strcmp(argv[arg], "-w")) { ws = WS_ONLY; continue; }
	if (!strcmp(argv[arg], "-W")) { ws = WS_RESET; continue; }
	if (!strcmp(argv[arg], "-R")) { order *= -1; continue; }
	if (!strcmp(argv[arg], "-h")) { usage(argv[0]); exit(0); }
	fprintf(stderr, "Invalid argument \"%s\".\n", argv[arg]);
	usage(argv[0]);
	exit(EXIT_FAILURE);
	}

	error = pm_kernel_create(&ker);
	if (error) {
	fprintf(stderr, "Error creating kernel interface -- "
	"does this kernel have pagemap?\n");
	exit(EXIT_FAILURE);
	}

	error = pm_kernel_pids(ker, &pids, &num_procs);
	if (error) {
	fprintf(stderr, "Error listing processes.\n");
	exit(EXIT_FAILURE);
	}

	procs = calloc(num_procs, sizeof(struct proc_info*));
	if (procs == NULL) {
	fprintf(stderr, "calloc: %s", strerror(errno));
	exit(EXIT_FAILURE);
	}

	for (i = 0; i < num_procs; i++) {
	procs[i] = malloc(sizeof(struct proc_info));
	if (procs[i] == NULL) {
	fprintf(stderr, "malloc: %s\n", strerror(errno));
	exit(EXIT_FAILURE);
	}
	procs[i]->pid = pids[i];
	pm_memusage_zero(&procs[i]->usage);
	error = pm_process_create(ker, pids[i], &proc);
	if (error) {
	fprintf(stderr, "warning: could not create process interface for %d\n", pids[i]);
	continue;
	}

	switch (ws) {
	case WS_OFF:
	error = pm_process_usage_flags(proc, &procs[i]->usage, flags_mask,
	required_flags);
	break;
	case WS_ONLY:
	error = pm_process_workingset(proc, &procs[i]->usage, 0);
	break;
	case WS_RESET:
	error = pm_process_workingset(proc, NULL, 1);
	break;
	}

	if (error) {
	fprintf(stderr, "warning: could not read usage for %d\n", pids[i]);
	}

	if (ws != WS_RESET && procs[i]->usage.swap) {
	has_swap = true;
	}

	pm_process_destroy(proc);
	}

	free(pids);

	if (ws == WS_RESET) exit(0);

	j = 0;
	for (i = 0; i < num_procs; i++) {
	if (procs[i]->usage.vss) {
	procs[j++] = procs[i];
	} else {
	free(procs[i]);
	}
	}
	num_procs = j;

	qsort(procs, num_procs, sizeof(procs[0]), compfn);

	printf("%5s ", "PID");
	if (ws) {
	printf("%s %7s %7s ", "WRss", "WPss", "WUss");
	if (has_swap) {
	printf("%7s ", "WSwap");
	}
	} else {
	printf("%8s %7s %7s %7s ", "Vss", "Rss", "Pss", "Uss");
	if (has_swap) {
	printf("%7s ", "Swap");
	}
	}

	printf("%s\n", "cmdline");

	total_pss = 0;
	total_uss = 0;
	total_swap = 0;

	for (i = 0; i < num_procs; i++) {
	if (getprocname(procs[i]->pid, cmdline, (int)sizeof(cmdline)) < 0) {
	/*
	* Something is probably seriously wrong if writing to the stack
	* failed.
	*/
	free(procs[i]);
	continue;
	}

	total_pss += procs[i]->usage.pss;
	total_uss += procs[i]->usage.uss;
	total_swap += procs[i]->usage.swap;

	printf("%5d ", procs[i]->pid);

	if (ws) {
	printf("%6zuK %6zuK %6zuK ",
	procs[i]->usage.rss / 1024,
	procs[i]->usage.pss / 1024,
	procs[i]->usage.uss / 1024
	);
	} else {
	printf("%7zuK %6zuK %6zuK %6zuK ",
	procs[i]->usage.vss / 1024,
	procs[i]->usage.rss / 1024,
	procs[i]->usage.pss / 1024,
	procs[i]->usage.uss / 1024
	);
	}

	if (has_swap) {
	printf("%6zuK ", procs[i]->usage.swap / 1024);
	}

	printf("%s\n", cmdline);

	free(procs[i]);
	}

	free(procs);

	/* Print the separator line */
	printf("%5s ", "");

	if (ws) {
	printf("%7s %7s %7s ", "", "------", "------");
	} else {
	printf("%8s %7s %7s %7s ", "", "", "------", "------");
	}

	if (has_swap) {
	printf("%7s ", "------");
	}

	printf("%s\n", "------");

	/* Print the total line */
	printf("%5s ", "");
	if (ws) {
	printf("%7s %6" PRIu64 "K %" PRIu64 "K ",
	"", total_pss / 1024, total_uss / 1024);
	} else {
	printf("%8s %7s %6" PRIu64 "K %6" PRIu64 "K ",
	"", "", total_pss / 1024, total_uss / 1024);
	}

	if (has_swap) {
	printf("%6" PRIu64 "K ", total_swap / 1024);
	}

	printf("TOTAL\n");

	printf("\n");
	print_mem_info();

	return 0;
	}

	static void usage(char *myname) {
	fprintf(stderr, "Usage: %s [ -W ] [ -v \| -r \| -p \| -u \| -s \| -h ]\n"
	" -v Sort by VSS.\n"
	" -r Sort by RSS.\n"
	" -p Sort by PSS.\n"
	" -u Sort by USS.\n"
	" -s Sort by swap.\n"
	" (Default sort order is PSS.)\n"
	" -R Reverse sort order (default is descending).\n"
	" -c Only show cached (storage backed) pages\n"
	" -C Only show non-cached (ram/swap backed) pages\n"
	" -k Only show pages collapsed by KSM\n"
	" -w Display statistics for working set only.\n"
	" -W Reset working set of all processes.\n"
	" -h Display this help screen.\n",
	myname);
	}

	/*
	* Get the process name for a given PID. Inserts the process name into buffer
	* buf of length len. The size of the buffer must be greater than zero to get
	* any useful output.
	*
	* Note that fgets(3) only declares length as an int, so our buffer size is
	* also declared as an int.
	*
	* Returns 0 on success, a positive value on partial success, and -1 on
	* failure. Other interesting values:
	* 1 on failure to create string to examine proc cmdline entry
	* 2 on failure to open proc cmdline entry
	* 3 on failure to read proc cmdline entry
	*/
	static int getprocname(pid_t pid, char *buf, int len) {
	char *filename;
	FILE *f;
	int rc = 0;
	static const char* unknown_cmdline = "<unknown>";

	if (len <= 0) {
	return -1;
	}

	if (asprintf(&filename, "/proc/%d/cmdline", pid) < 0) {
	rc = 1;
	goto exit;
	}

	f = fopen(filename, "r");
	if (f == NULL) {
	rc = 2;
	goto releasefilename;
	}

	if (fgets(buf, len, f) == NULL) {
	rc = 3;
	goto closefile;
	}

	closefile:
	(void) fclose(f);
	releasefilename:
	free(filename);
	exit:
	if (rc != 0) {
	/*
	* The process went away before we could read its process name. Try
	* to give the user "<unknown>" here, but otherwise they get to look
	* at a blank.
	*/
	if (strlcpy(buf, unknown_cmdline, (size_t)len) >= (size_t)len) {
	rc = 4;
	}
	}

	return rc;
	}

	static int numcmp(uint64_t a, uint64_t b) {
	if (a < b) return -1;
	if (a > b) return 1;
	return 0;
	}

	#define create_sort(field, compfn) \
	static int sort_by_ ## field (const void a, const void b) { \
	return order * compfn( \
	(((struct proc_info*)a))->usage.field, \
	(((struct proc_info*)b))->usage.field \
	); \
	}

	create_sort(vss, numcmp)
	create_sort(rss, numcmp)
	create_sort(pss, numcmp)
	create_sort(uss, numcmp)
	create_sort(swap, numcmp)