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top: parent total cpu includes collapsed children, pgm

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Now, when a parent's children have been collapsed, the
cpu used by those unseen tasks will disappear no more.
Instead such tics will be added to the parent's total.

[ if one wished a return to the 'land of lost tics', ]
[ the '#define TREE_VCPUOFF' directive is available. ]

------------------------------------------------------
Note: With collapsible parents now displaying children
cpu usage, it will eventually be noticed the cpu stats
for the summary area and task areas often vary widely.

It's worth a reminder that for top's summary area each
individual cpu and the cpu summary is limited to 100%,
regardless of how many tics a linux kernel may export.

An individual task is limited to 100% times the number
of threads. But, in no case will cpu usage ever exceed
100% times total number of processors. Such limits are
further reduced under 'Solaris' mode ('I' toggle off).
In this mode, a task cpu usage will never exceed 100%.
These limits will now also apply to collapsed parents.

In addition to those influences, results are subjected
to kernel timer sampling anomalies and the distortions
inherent in a small sample size, made worse by smaller
delay intervals. Often there is just 1 or 2 tics for a
few tasks at smaller intervals such as: 1/10th second.

Anyway, should questions on this subject arise, a good
starting point, beyond the reminders above, is the 1st
link listed below. Those other links were derivatives.

Reference(s):
. from the kernel documentation
https://www.kernel.org/doc/Documentation/cpu-load.txt
. as mentioned in the above kernel documentation
https://lkml.org/lkml/2007/2/12/6
. from above, with many more links on the subject
https://www.boblycat.org/~malc/apc/

Signed-off-by: Jim Warner <james.warner@comcast.net>

top: parent total cpu includes collapsed children, pgm
This commit is contained in:
Jim Warner 2018-06-25 00:00:00 -05:00 committed by Craig Small
parent e66c36794a
commit 3da7318683
2 changed files with 23 additions and 2 deletions
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24
top/top.c
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@ -4684,13 +4684,16 @@ static inline int wins_usrselect (const WIN_t *q, const int idx) {
static proc_t **Seed_ppt; // temporary win ppt pointer
static proc_t **Tree_ppt; // forest_create will resize
static int Tree_idx; // frame_make resets to zero
/* those next two support collapse/expand children. the Hide_pid
/* the next three support collapse/expand children. the Hide_pid
array holds parent pids whose children have been manipulated.
positive pid values represent parents with collapsed children
while a negative pid value means children have been expanded.
( both of these are managed under the 'keys_task()' routine ) */
static int *Hide_pid; // collapsible process array
static int Hide_tot; // total used in above array
#ifndef TREE_VCPUOFF
static int *Hide_cpu; // accum tics from collapsed
#endif
/*
* This little recursive guy is the real forest view workhorse.
@ -4745,6 +4748,9 @@ static void forest_create (WIN_t *q) {
hwmsav = Frame_maxtask;
Tree_ppt = alloc_r(Tree_ppt, sizeof(proc_t*) * hwmsav);
Hide_pid = alloc_r(Hide_pid, sizeof(int) * hwmsav);
#ifndef TREE_VCPUOFF
Hide_cpu = alloc_r(Hide_cpu, sizeof(int) * hwmsav);
#endif
}
#ifndef TREE_SCANALL
@ -4754,6 +4760,9 @@ static void forest_create (WIN_t *q) {
if (!Seed_ppt[i]->pad_3) // real & pseudo parents == zero
forest_adds(i, 0); // add a parent and its children
}
#ifndef TREE_VCPUOFF
memset(Hide_cpu, 0, sizeof(int) * Frame_maxtask);
#endif
/* we're borrowing some pad bytes in the proc_t,
pad_2: 'x' means a collapsed thread, 'z' means an unseen child
pad_3: where level number is stored (0 - 100) */
@ -4767,6 +4776,9 @@ static void forest_create (WIN_t *q) {
while (j+1 < Frame_maxtask && Tree_ppt[j+1]->pad_3 > level) {
Tree_ppt[j+1]->pad_2 = 'z';
#ifndef TREE_VCPUOFF
Hide_cpu[parent] += Tree_ppt[j+1]->pcpu;
#endif
children = 1;
++j;
}
@ -5987,10 +5999,18 @@ static const char *task_show (const WIN_t *q, const int idx) {
cp = make_num(p->processor, W, Jn, AUTOX_NO, 0);
break;
case EU_CPU:
{ float u = (float)p->pcpu * Frame_etscale;
{ float u = (float)p->pcpu;
#ifndef TREE_VCPUOFF
// Hide_cpu entry is always zero, unless we're a collapsed parent
u += Hide_cpu[idx];
u *= Frame_etscale;
if (p->pad_2 != 'x' && u > 100.0 * p->nlwp) u = 100.0 * p->nlwp;
#else
u *= Frame_etscale;
/* process can't use more %cpu than number of threads it has
( thanks Jaromir Capik <jcapik@redhat.com> ) */
if (u > 100.0 * p->nlwp) u = 100.0 * p->nlwp;
#endif
if (u > Cpu_pmax) u = Cpu_pmax;
cp = scale_pcnt(u, W, Jn);
}

1
top/top.h
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@ -56,6 +56,7 @@
//#define TERMIOS_ONLY /* just limp along with native input only */
//#define TREE_NORESET /* sort keys do NOT force forest view OFF */
//#define TREE_SCANALL /* rescan array w/ forest view, avoid sort */
//#define TREE_VCPUOFF /* a collapsed parent excludes child's cpu */
//#define TREE_VPROMPT /* pid collapse/expand prompt, vs. top row */
//#define TREE_VWINALL /* pid collapse/expand impacts all windows */
//#define USE_X_COLHDR /* emphasize header vs. whole col, for 'x' */