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Slim out joinset
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This commit removes a joinset in the inner polling loop of the procfs
sampler. The existence of the joinset makes calculation of total_pss,
total_rss more difficult and its unclear that there is a performance
boost by its existence.

Signed-off-by: Brian L. Troutwine <brian.troutwine@datadoghq.com>
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@blt
blt committed Dec 6, 2024
1 parent d767aa4 commit 88a426e
Showing 1 changed file with 72 additions and 78 deletions.
150 changes: 72 additions & 78 deletions lading/src/observer/linux/procfs.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -85,14 +85,12 @@ impl Sampler {
clippy::cast_possible_wrap
)]
pub(crate) async fn poll(&mut self) -> Result<(), Error> {
let mut joinset = tokio::task::JoinSet::new();
// Key for this map is (pid, basename/exe, cmdline)
let mut samples: FxHashMap<ProcessIdentifier, Sample> = FxHashMap::default();

let mut total_processes: u64 = 0;
// We maintain a tally of the total RSS consumed by the parent process
// and its children. This is used for analysis and for cooperation with
// the throttle (through RSS_BYTES).
// We maintain a tally of the total RSS and PSS consumed by the parent
// process and its children.
let mut total_rss: u64 = 0;

// Calculate the ticks since machine uptime. This will be important
Expand Down Expand Up @@ -291,83 +289,81 @@ impl Sampler {
// If a previous call to process.status() failed due to a lack of ptrace permissions,
// then we assume smaps operations will fail as well.
if has_ptrace_perm {
joinset.spawn(async move {
// `/proc/{pid}/smaps`
let memory_regions = match memory::smaps::Regions::from_pid(pid) {
Ok(memory_regions) => memory_regions,
Err(e) => {
// We don't want to bail out entirely if we can't read stats
// which will happen if we don't have permissions or, more
// likely, the process has exited.
warn!("Couldn't process `/proc/{pid}/smaps`: {}", e);
return;
}
};
for (pathname, measures) in memory_regions.aggregate_by_pathname() {
let labels = [
("pid", format!("{pid}")),
("exe", basename.clone()),
("cmdline", cmdline.clone()),
("comm", comm.clone()),
("pathname", pathname),
];
gauge!("smaps.rss.by_pathname", &labels).set(measures.rss as f64);
gauge!("smaps.pss.by_pathname", &labels).set(measures.pss as f64);
gauge!("smaps.swap.by_pathname", &labels).set(measures.swap as f64);
gauge!("smaps.size.by_pathname", &labels).set(measures.size as f64);

if let Some(m) = measures.private_clean {
gauge!("smaps.private_clean.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.private_dirty {
gauge!("smaps.private_dirty.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.shared_clean {
gauge!("smaps.shared_clean.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.shared_dirty {
gauge!("smaps.shared_dirty.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.referenced {
gauge!("smaps.referenced.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.anonymous {
gauge!("smaps.anonymous.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.lazy_free {
gauge!("smaps.lazy_free.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.anon_huge_pages {
gauge!("smaps.anon_huge_pages.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.shmem_pmd_mapped {
gauge!("smaps.shmem_pmd_mapped.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.shared_hugetlb {
gauge!("smaps.shared_hugetlb.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.private_hugetlb {
gauge!("smaps.private_hugetlb.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.file_pmd_mapped {
gauge!("smaps.file_pmd_mapped.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.locked {
gauge!("smaps.locked.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.swap_pss {
gauge!("smaps.swap_pss.by_pathname", &labels).set(m as f64);
// `/proc/{pid}/smaps`
match memory::smaps::Regions::from_pid(pid) {
Ok(memory_regions) => {
for (pathname, measures) in memory_regions.aggregate_by_pathname() {
let labels = [
("pid", format!("{pid}")),
("exe", basename.clone()),
("cmdline", cmdline.clone()),
("comm", comm.clone()),
("pathname", pathname),
];
gauge!("smaps.rss.by_pathname", &labels).set(measures.rss as f64);
gauge!("smaps.pss.by_pathname", &labels).set(measures.pss as f64);
gauge!("smaps.swap.by_pathname", &labels).set(measures.swap as f64);
gauge!("smaps.size.by_pathname", &labels).set(measures.size as f64);

if let Some(m) = measures.private_clean {
gauge!("smaps.private_clean.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.private_dirty {
gauge!("smaps.private_dirty.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.shared_clean {
gauge!("smaps.shared_clean.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.shared_dirty {
gauge!("smaps.shared_dirty.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.referenced {
gauge!("smaps.referenced.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.anonymous {
gauge!("smaps.anonymous.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.lazy_free {
gauge!("smaps.lazy_free.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.anon_huge_pages {
gauge!("smaps.anon_huge_pages.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.shmem_pmd_mapped {
gauge!("smaps.shmem_pmd_mapped.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.shared_hugetlb {
gauge!("smaps.shared_hugetlb.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.private_hugetlb {
gauge!("smaps.private_hugetlb.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.file_pmd_mapped {
gauge!("smaps.file_pmd_mapped.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.locked {
gauge!("smaps.locked.by_pathname", &labels).set(m as f64);
}
if let Some(m) = measures.swap_pss {
gauge!("smaps.swap_pss.by_pathname", &labels).set(m as f64);
}
}
}

// `/proc/{pid}/smaps_rollup`
if let Err(err) = memory::smaps_rollup::poll(pid, &labels).await {
// We don't want to bail out entirely if we can't read smap rollup
Err(err) => {
// We don't want to bail out entirely if we can't read stats
// which will happen if we don't have permissions or, more
// likely, the process has exited.
warn!("Couldn't process `/proc/{pid}/smaps_rollup`: {err}");
warn!("Couldn't process `/proc/{pid}/smaps`: {err}");
}
});
}

// `/proc/{pid}/smaps_rollup`
if let Err(err) = memory::smaps_rollup::poll(pid, &labels).await {
// We don't want to bail out entirely if we can't read smap rollup
// which will happen if we don't have permissions or, more
// likely, the process has exited.
warn!("Couldn't process `/proc/{pid}/smaps_rollup`: {err}");
}
}
}

Expand Down Expand Up @@ -435,8 +431,6 @@ impl Sampler {
self.previous_totals = total_sample;
self.previous_samples = samples;

// drain any tasks before returning
while (joinset.join_next().await).is_some() {}
Ok(())
}
}
Expand Down

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