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library: minimize the use of 'cleanup_stacks' routines

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Some parts of our newlib implementation are the result
of functions which have been propagated from module to
module. In particular, those 'cleanup_stacks' routines
are all similar & likely originated in the <pids> api.

In that interface there was a need to free dynamically
acquired memory before the result structure was reused
to satisfy subsequent 'get', 'select' or 'reap' calls.
This, in turn, led to a concept of 'dirty' stacks with
the need to call one of two 'cleanup_stack' functions.

None of the remaining interfaces deal with such memory
yet they each had their own 'cleanup_stack' functions.
Those functions were responsible for resetting each of
the result unions to zero, excluding any 'noop' items.

The bottom line is that for all interfaces, repetitive
calls would require iterating through the stack(s) two
separate times: once to 'cleanup' another to 'assign'.

With this commit we will reduce iterations to just the
'assign' routine. A reset to zero will be accomplished
in the 'extra' item set routine (which is the only one
actually requiring any reset). All other items will be
reinitialized automatically by a new current set value
or upon reallocation when an items compliment changes.

In the <pids> interface, any freeing of dynamic memory
could have been accomplished by adding that 'freefunc'
check to the 'assign' function. However, that requires
an Item_table test with every item. Instead, we'll now
satisfy such needs as the very first step in those set
functions responsible for dynamically acquired memory.

[ the <pids> api retains 2 'cleanup_stack' functions ]
[ to accommodate stack(s) 'reset' & to serve 'unref' ]

Lastly, all the 'itemize_stack' functions were tweaked
by eliminating an unnecessary initialization of result
unions. That objective was already accomplished by the
calloc() in a 'stacks_alloc' function or the remaining
'cleanup_stack' routine found in the <pids> interface.

Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit is contained in:
Jim Warner
2019-05-22 00:00:00 -05:00
committed by Craig Small
parent 22a3bcbd6d
commit 40883a0b85
6 changed files with 33 additions and 221 deletions
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41
proc/stat.c
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@ -88,7 +88,6 @@ struct item_support {
struct ext_support {
struct item_support *items; // how these stacks are configured
struct stacks_extent *extents; // anchor for these extents
int dirty_stacks;
};
struct tic_support {
@ -144,8 +143,8 @@ struct stat_info {
(void)T; R->result. t = ( S->new . x - S->old. x ); \
if (R->result. t < 0) R->result. t = 0; }
setDECL(noop) { (void)R; (void)S; (void)T; }
setDECL(extra) { (void)R; (void)S; (void)T; }
setDECL(noop) { (void)R; (void)S; (void)T; }
setDECL(extra) { (void)S; (void)T; R->result.ull_int = 0; }
setDECL(TIC_ID) { (void)S; R->result.s_int = T->id; }
setDECL(TIC_NUMA_NODE) { (void)S; R->result.s_int = T->numa_node; }
@ -365,34 +364,6 @@ static inline void stat_assign_results (
} // end: stat_assign_results
static inline void stat_cleanup_stack (
struct stat_result *this)
{
for (;;) {
if (this->item >= STAT_logical_end)
break;
if (this->item > STAT_noop)
this->result.ull_int = 0;
++this;
}
} // end: stat_cleanup_stack
static inline void stat_cleanup_stacks_all (
struct ext_support *this)
{
struct stacks_extent *ext = this->extents;
int i;
while (ext) {
for (i = 0; ext->stacks[i]; i++)
stat_cleanup_stack(ext->stacks[i]->head);
ext = ext->next;
};
this->dirty_stacks = 0;
} // end: stat_cleanup_stacks_all
static inline void stat_derive_unique (
struct hist_tic *this)
{
@ -449,7 +420,6 @@ static inline struct stat_result *stat_itemize_stack (
for (i = 0; i < depth; i++) {
p->item = items[i];
p->result.ull_int = 0;
++p;
}
return p_sav;
@ -762,8 +732,6 @@ static int stat_stacks_fetch (
return -1; // here, errno was set to ENOMEM
memcpy(this->anchor, ext->stacks, sizeof(void *) * n_alloc);
}
if (this->fetch.dirty_stacks)
stat_cleanup_stacks_all(&this->fetch);
// iterate stuff --------------------------------------
for (i = 0; i < n_inuse; i++) {
@ -790,7 +758,6 @@ static int stat_stacks_fetch (
memcpy(this->result.stacks, this->anchor, sizeof(void *) * i);
this->result.stacks[i] = NULL;
this->result.total = i;
this->fetch.dirty_stacks = 1;
// callers beware, this might be zero (maybe no libnuma.so) ...
return this->result.total;
@ -832,11 +799,7 @@ static struct stat_stack *stat_update_single_stack (
&& !(stat_stacks_alloc(this, 1)))
return NULL;
if (this->dirty_stacks)
stat_cleanup_stacks_all(this);
stat_assign_results(this->extents->stacks[0], &info->sys_hist, &info->cpu_hist);
this->dirty_stacks = 1;
return this->extents->stacks[0];
} // end: stat_update_single_stack