diff options
| -rw-r--r-- | libbb/Config.in | 7 | ||||
| -rw-r--r-- | libbb/procps.c | 55 |
2 files changed, 60 insertions, 2 deletions
diff --git a/libbb/Config.in b/libbb/Config.in index 5f4e416dd..f82a2b1ce 100644 --- a/libbb/Config.in +++ b/libbb/Config.in @@ -26,6 +26,13 @@ config MD5_SIZE_VS_SPEED 2 3.0 5088 3 (smallest) 5.1 4912 +config FEATURE_FAST_TOP + bool "Faster /proc scanning code (+100 bytes)" + default n + help + This option makes top (and ps) ~20% faster (or 20% less CPU hungry), + but code size is slightly bigger. + config FEATURE_ETC_NETWORKS bool "Support for /etc/networks" default n diff --git a/libbb/procps.c b/libbb/procps.c index 1e2495a5a..879cc105a 100644 --- a/libbb/procps.c +++ b/libbb/procps.c @@ -107,6 +107,28 @@ void free_procps_scan(procps_status_t* sp) free(sp); } +#if ENABLE_FEATURE_FAST_TOP +/* We cut a lot of corners here for speed */ +static unsigned long fast_strtoul_10(char *str, char **endptr) +{ + char c; + unsigned long n = *str - '0'; + + while ((c = *++str) != ' ') + n = n*10 + (c - '0'); + + *endptr = str + 1; /* We skip trailing space! */ + return n; +} +static char *skip_fields(char *str, int count) +{ + do { + str = skip_non_whitespace(str); str++; + } while (--count); + return str; +} +#endif + void BUG_comm_size(void); procps_status_t* procps_scan(procps_status_t* sp, int flags) { @@ -160,7 +182,9 @@ procps_status_t* procps_scan(procps_status_t* sp, int flags) if (flags & PSSCAN_STAT) { char *cp; +#if !ENABLE_FEATURE_FAST_TOP unsigned long vsz, rss; +#endif int tty; /* see proc(5) for some details on this */ @@ -175,6 +199,8 @@ procps_status_t* procps_scan(procps_status_t* sp, int flags) if (sizeof(sp->comm) < 16) BUG_comm_size(); sscanf(buf, "%*s (%15c", sp->comm); + +#if !ENABLE_FEATURE_FAST_TOP n = sscanf(cp+2, "%c %u " /* state, ppid */ "%u %u %d %*s " /* pgid, sid, tty, tpgid */ @@ -197,6 +223,8 @@ procps_status_t* procps_scan(procps_status_t* sp, int flags) &rss); if (n != 10) break; + sp->vsz = vsz >> 10; /* vsize is in bytes and we want kb */ + sp->rss = rss >> 10; sp->tty_str[0] = '?'; /* sp->tty_str[1] = '\0'; - done by memset */ @@ -204,6 +232,31 @@ procps_status_t* procps_scan(procps_status_t* sp, int flags) snprintf(sp->tty_str, sizeof(sp->tty_str), "%u,%u", (tty >> 8) & 0xfff, /* major */ (tty & 0xff) | ((tty >> 12) & 0xfff00)); +#else +/* This costs ~100 bytes more but makes top faster by 20% + * If you run 10000 processes, this may be important for you */ + cp += 2; + sp->state[0] = *cp++; cp++; + sp->ppid = fast_strtoul_10(cp, &cp); + sp->pgid = fast_strtoul_10(cp, &cp); + sp->sid = fast_strtoul_10(cp, &cp); + sp->tty_str[0] = '?'; + /* sp->tty_str[1] = '\0'; - done by memset */ + tty = fast_strtoul_10(cp, &cp); + if (tty) /* tty field of "0" means "no tty" */ + snprintf(sp->tty_str, sizeof(sp->tty_str), "%u,%u", + (tty >> 8) & 0xfff, /* major */ + (tty & 0xff) | ((tty >> 12) & 0xfff00)); + cp = skip_fields(cp, 6); /* tpgid, flags, min_flt, cmin_flt, maj_flt, cmaj_flt */ + sp->utime = fast_strtoul_10(cp, &cp); + sp->stime = fast_strtoul_10(cp, &cp); + cp = skip_fields(cp, 3); /* cutime, cstime, priority */ + tasknice = fast_strtoul_10(cp, &cp); + cp = skip_fields(cp, 3); /* timeout, it_real_value, start_time */ + sp->vsz = fast_strtoul_10(cp, &cp) >> 10; /* vsize is in bytes and we want kb */ + sp->rss = fast_strtoul_10(cp, &cp) >> 10; +#endif + if (sp->vsz == 0 && sp->state[0] != 'Z') sp->state[1] = 'W'; else @@ -215,8 +268,6 @@ procps_status_t* procps_scan(procps_status_t* sp, int flags) else sp->state[2] = ' '; - sp->vsz = vsz >> 10; /* vsize is in bytes and we want kb */ - sp->rss = rss >> 10; } if (flags & PSSCAN_CMD) { |