Hi Bernhard, I'm sending new patch and the result of bloatcheck. Can you review these and give me your thoughts? Just let me know if you think that the code size needs to be reduced.
Br-Matthew
________________________________
From: Bernhard Reutner-Fischer <rep.dot....@gmail.com>
Sent: Tuesday, February 13, 2024 7:16 PM
To: Matthew Chae <matthew.c...@axis.com>
Cc: rep.dot....@gmail.com <rep.dot....@gmail.com>; David Laight
<david.lai...@aculab.com>; 'Denys Vlasenko' <vda.li...@googlemail.com>;
busybox@busybox.net <busybox@busybox.net>; Christopher Wong
<christopher.w...@axis.com>
Subject: Re: fix large PID overflow their column in top command
On Mon, 5 Feb 2024 09:56:20 +0000
Matthew Chae <matthew.c...@axis.com> wrote:
> Hi David,
>
> I'm sending an improved patch based on your comments.
>
> Not only does it not care about the PID_MAX value,
> it searches all the contents to be output to recognize the required column
> width
> and dynamically allocates the space for PID and PPID appropriately without
> creating a lot of empty space.
>
> Additionally, this patch still allows user names to be displayed up to 8
> characters without truncation.
>
> Can you look through the attachment?
Unfortunately the patch does not apply to current master.
How much would your patch add to the size? Can you bring it down to a
minimum?
See make baseline; apply the patch;make bloatcheck
thanks
> (0002-Allocate-PID-PPID-space-dynamically-in-top-command.patch)
>
> BR-Matthew Chae
> ________________________________
> From: David Laight <david.lai...@aculab.com>
> Sent: Thursday, November 23, 2023 6:10 PM
> To: 'Denys Vlasenko' <vda.li...@googlemail.com>; Matthew Chae
> <matthew.c...@axis.com>
> Cc: busybox@busybox.net <busybox@busybox.net>; Christopher Wong
> <christopher.w...@axis.com>
> Subject: RE: fix large PID overflow their column in top command
>
> ...
> > + fp = xfopen_for_read("/proc/sys/kernel/pid_max");
> > + if (!fgets(pid_buf, PID_DIGITS_MAX + 1, fp)) {
> > ...
> > + if (strncmp(pid_buf, "32768", 5) == 0)
> > + pid_digits_num = 5;
> > + else
> > + pid_digits_num = PID_DIGITS_MAX;
> >
> > The logic above is not sound. Even if sysctl kernel.pid_max
> > is 32768, there can be already running processes with pids > 99999.
>
> It's also probably wrong for pretty much all other values.
>
> I'd just base the column width on strlen(pid_buf) with a minimum
> value of 5.
>
> It is unlikely that pid_max has been reduced - so column overflow
> it that case probably doesn't really matter.
>
> The more interesting case is really a system with a very large pid_max
> that has never run many processes.
> You don't really want lots of blank space.
>
> I can't remember whether top reads everything before doing any output?
> Since the output is sorted it probably almost always does.
> In which case it knows the column width it will need.
>
> I did post a patch a while back that enabled 'Irix mode'.
> (100% cpu is one cpu at 100%, not all cpus at 100%)
> Maybe I should dig it out again.
>
> David
>
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1
> 1PT, UK
> Registration No: 1397386 (Wales)
bloatcheck_top
Description: bloatcheck_top
From a3d8d00fec2514b52bd253911e0fab2205c4e1ef Mon Sep 17 00:00:00 2001
From: Matthew Chae <matth...@axis.com>
Date: Wed, 14 Feb 2024 14:41:18 +0100
Subject: [PATCH] Allocate PID/PPID space dynamically in top command
The presence of a large number of PID and PPID digits in the column may
cause overflow, making it impossible to display the entire data
accurately. This dynamically allocates the appropriate space for the
number of digits in the PID and PPID, ensuring the correct
representation of values in each column and guaranteeing a clean
display.
Reviewed-by: Christopher Wong <christopher.w...@axis.com>
Signed-off-by: Matthew(Sukyoung) Chae <matth...@axis.com>
---
procps/top.c | 83 ++++++++++++++++++++++++++++++++--------------------
1 file changed, 51 insertions(+), 32 deletions(-)
diff --git a/procps/top.c b/procps/top.c
index 09d31c673..4f5f0e4a0 100644
--- a/procps/top.c
+++ b/procps/top.c
@@ -602,6 +602,22 @@ static unsigned long display_header(int scr_width, int *lines_rem_p)
return meminfo[MI_MEMTOTAL];
}
+static int count_digits(unsigned num)
+{
+ int cnt = 0;
+
+ if (num < 10)
+ return 1;
+
+ while (num > 0)
+ {
+ num /= 10;
+ cnt++;
+ }
+
+ return cnt;
+}
+
static NOINLINE void display_process_list(int lines_rem, int scr_width)
{
enum {
@@ -619,6 +635,30 @@ static NOINLINE void display_process_list(int lines_rem, int scr_width)
unsigned busy_jifs;
#endif
+#define PID_STR "PID"
+#define PPID_STR "PPID"
+#define DEFAULT_DIGIT_MIN 5
+
+ char top_title_str[scr_width + 1];
+ int lines = (lines_rem - 1);
+ unsigned pid_max = 0;
+ unsigned ppid_max = 0;
+ unsigned pid_digits_max = DEFAULT_DIGIT_MIN;
+ unsigned ppid_digits_max = DEFAULT_DIGIT_MIN;
+ top_status_t *s_tmp = top + G_scroll_ofs;
+
+ if (lines > ntop - G_scroll_ofs)
+ lines = ntop - G_scroll_ofs;
+
+ while (--lines >= 0) {
+ pid_max = MAX(pid_max, s_tmp->pid);
+ ppid_max = MAX(ppid_max, s_tmp->ppid);
+ s_tmp++;
+ }
+
+ pid_digits_max = MAX(pid_digits_max, count_digits(pid_max));
+ ppid_digits_max = MAX(ppid_digits_max, count_digits(ppid_max));
+
#if ENABLE_FEATURE_TOP_DECIMALS
# define UPSCALE 1000
typedef struct { unsigned quot, rem; } bb_div_t;
@@ -638,11 +678,15 @@ typedef struct { unsigned quot, rem; } bb_div_t;
#endif
/* what info of the processes is shown */
- printf(OPT_BATCH_MODE ? "%.*s" : ESC"[7m" "%.*s" ESC"[m", scr_width,
- " PID PPID USER STAT VSZ %VSZ"
+ snprintf(top_title_str, scr_width + 1,
+ "%*s%s %*s%s %s",
+ pid_digits_max - (int)strlen(PID_STR), " ", PID_STR,
+ ppid_digits_max - (int)strlen(PPID_STR), " ", PPID_STR,
+ "USER STAT VSZ %VSZ"
IF_FEATURE_TOP_SMP_PROCESS(" CPU")
IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE(" %CPU")
" COMMAND");
+ printf(OPT_BATCH_MODE ? "%.*s" : ESC"[7m" "%.*s" ESC"[m", scr_width, top_title_str);
lines_rem--;
/*
@@ -696,8 +740,6 @@ typedef struct { unsigned quot, rem; } bb_div_t;
lines_rem = ntop - G_scroll_ofs;
s = top + G_scroll_ofs;
while (--lines_rem >= 0) {
- int n;
- char *ppu;
char ppubuf[sizeof(int)*3 * 2 + 12];
char vsz_str_buf[8];
unsigned col;
@@ -709,39 +751,16 @@ typedef struct { unsigned quot, rem; } bb_div_t;
smart_ulltoa5(s->vsz, vsz_str_buf, " mgtpezy");
/* PID PPID USER STAT VSZ %VSZ [%CPU] COMMAND */
- n = sprintf(ppubuf, "%5u %5u %-8.8s", s->pid, s->ppid, get_cached_username(s->uid));
- ppu = ppubuf;
- if (n != 6+6+8) {
- /* Format PID PPID USER part into 6+6+8 chars:
- * shrink PID/PPID if possible, then truncate USER.
- * Tested on Linux 5.18.0:
- * sysctl kernel.pid_max=4194304 is the maximum allowed,
- * so PID and PPID are 7 chars wide at most.
- */
- char *p, *pp;
- if (*ppu == ' ') {
- do {
- ppu++, n--;
- if (n == 6+6+8)
- goto shortened;
- } while (*ppu == ' ');
- }
- pp = p = skip_non_whitespace(ppu) + 1;
- if (*p == ' ') {
- do
- p++, n--;
- while (n != 6+6+8 && *p == ' ');
- overlapping_strcpy(pp, p); /* shrink PPID */
- }
- ppu[6+6+8] = '\0'; /* truncate USER */
- }
- shortened:
+ snprintf(ppubuf, sizeof(ppubuf), "%*u %*u %-8.8s",
+ pid_digits_max, s->pid, ppid_digits_max, s->ppid,
+ get_cached_username(s->uid));
+
col = snprintf(line_buf, scr_width,
"\n" "%s %s %.5s" FMT
IF_FEATURE_TOP_SMP_PROCESS(" %3d")
IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE(FMT)
" ",
- ppu,
+ ppubuf,
s->state, vsz_str_buf,
SHOW_STAT(pmem)
IF_FEATURE_TOP_SMP_PROCESS(, s->last_seen_on_cpu)
--
2.30.2
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