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[RFC] virtio-balloon: Add free page reporting hinting #5491

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[RFC] virtio-balloon: Add free page reporting hinting #5491

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5c9e4c7
virtio-balloon: Add free page reporting
JackThomson2 Oct 22, 2025
1ca36f2
virtio-balloon: Add free page hinting
JackThomson2 Oct 22, 2025
59e8fb6
virtio-balloon: Add api for free page hinting
JackThomson2 Oct 23, 2025
90621d3
virtio-balloon: Add metrics for hinting/reporting
JackThomson2 Oct 23, 2025
36eafae
test: Add API hinting endpoints
JackThomson2 Oct 23, 2025
fd88929
test: Add integration tests for hinting/reporting
JackThomson2 Oct 23, 2025
41ed063
test: Add unit tests for hint/reporting
JackThomson2 Oct 23, 2025
8dcf4fd
virtio-balloon: Drop huge page restriction
JackThomson2 Oct 24, 2025
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44 changes: 33 additions & 11 deletions resources/overlay/usr/local/bin/fast_page_fault_helper.c
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
#include <sys/mman.h> // mmap
#include <time.h> // clock_gettime
#include <fcntl.h> // open
#include <getopt.h> // getopt
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@kalyazin kalyazin Oct 30, 2025

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nit: can extract the update to the helper into a commit and explain the changes

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@JackThomson2 JackThomson2 Oct 30, 2025

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Makes sense, I will do!


#define MEM_SIZE_MIB (128 * 1024 * 1024)
#define NANOS_PER_SEC 1000000000
Expand All @@ -30,20 +31,39 @@ void touch_memory(void *mem, size_t size, char val) {

int main() {
sigset_t set;
int signal;
int signal, character;
void *ptr;
struct timespec start, end;
long duration_nanos;
FILE *out_file;

sigemptyset(&set);
if (sigaddset(&set, SIGUSR1) == -1) {
perror("sigaddset");
return 1;
char *options = 0;
int longindex = 0;
int signal_wait = 1;

struct option longopts[] = {
{"nosignal", no_argument, NULL, 's'},
{NULL, 0, NULL, 0}
};

while((character = getopt_long(argc, argv, "s", longopts, &longindex)) != -1) {
switch (character) {
case 's':
signal_wait = 0;
break;
}
}
if (sigprocmask(SIG_BLOCK, &set, NULL) == -1) {
perror("sigprocmask");
return 1;

if (signal_wait) {
sigemptyset(&set);
if (sigaddset(&set, SIGUSR1) == -1) {
perror("sigaddset");
return 1;
}
if (sigprocmask(SIG_BLOCK, &set, NULL) == -1) {
perror("sigprocmask");
return 1;
}
}

ptr = mmap(NULL, MEM_SIZE_MIB, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
Expand All @@ -53,9 +73,11 @@ int main() {
return 1;
}

touch_memory(ptr, MEM_SIZE_MIB, 1);
if (signal_wait) {
touch_memory(ptr, MEM_SIZE_MIB, 1);

sigwait(&set, &signal);
sigwait(&set, &signal);
}

clock_gettime(CLOCK_BOOTTIME, &start);
touch_memory(ptr, MEM_SIZE_MIB, 2);
Expand All @@ -76,4 +98,4 @@ int main() {
}

return 0;
}
}
76 changes: 74 additions & 2 deletions src/firecracker/src/api_server/parsed_request.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -78,7 +78,7 @@ impl TryFrom<&Request> for ParsedRequest {

match (request.method(), path, request.body.as_ref()) {
(Method::Get, "", None) => parse_get_instance_info(),
(Method::Get, "balloon", None) => parse_get_balloon(path_tokens.next()),
(Method::Get, "balloon", None) => parse_get_balloon(path_tokens),
(Method::Get, "version", None) => parse_get_version(),
(Method::Get, "vm", None) if path_tokens.next() == Some("config") => {
Ok(ParsedRequest::new_sync(VmmAction::GetFullVmConfig))
Expand All @@ -104,7 +104,7 @@ impl TryFrom<&Request> for ParsedRequest {
(Method::Put, "vsock", Some(body)) => parse_put_vsock(body),
(Method::Put, "entropy", Some(body)) => parse_put_entropy(body),
(Method::Put, _, None) => method_to_error(Method::Put),
(Method::Patch, "balloon", Some(body)) => parse_patch_balloon(body, path_tokens.next()),
(Method::Patch, "balloon", body) => parse_patch_balloon(body, path_tokens),
(Method::Patch, "drives", Some(body)) => parse_patch_drive(body, path_tokens.next()),
(Method::Patch, "machine-config", Some(body)) => parse_patch_machine_config(body),
(Method::Patch, "mmds", Some(body)) => parse_patch_mmds(body),
Expand Down Expand Up @@ -175,6 +175,9 @@ impl ParsedRequest {
Self::success_response_with_data(balloon_config)
}
VmmData::BalloonStats(stats) => Self::success_response_with_data(stats),
VmmData::HintingStatus(hinting_status) => {
Self::success_response_with_data(hinting_status)
}
VmmData::InstanceInformation(info) => Self::success_response_with_data(info),
VmmData::VmmVersion(version) => Self::success_response_with_data(
&serde_json::json!({ "firecracker_version": version.as_str() }),
Expand Down Expand Up @@ -325,6 +328,7 @@ pub mod tests {
use micro_http::HttpConnection;
use vmm::builder::StartMicrovmError;
use vmm::cpu_config::templates::test_utils::build_test_template;
use vmm::devices::virtio::balloon::device::HintingStatus;
use vmm::resources::VmmConfig;
use vmm::rpc_interface::VmmActionError;
use vmm::vmm_config::balloon::{BalloonDeviceConfig, BalloonStats};
Expand Down Expand Up @@ -474,6 +478,17 @@ pub mod tests {
&parsed_request,
Err(RequestError::Generic(StatusCode::BadRequest, s)) if s == "Empty PATCH request.",
));

sender
.write_all(http_request("PATCH", "/balloon", None).as_bytes())
.unwrap();
connection.try_read().unwrap();
let req = connection.pop_parsed_request().unwrap();
let parsed_request = ParsedRequest::try_from(&req);
assert!(matches!(
&parsed_request,
Err(RequestError::Generic(StatusCode::BadRequest, s)) if s == "Empty PATCH request.",
));
}

#[test]
Expand Down Expand Up @@ -559,6 +574,9 @@ pub mod tests {
VmmData::BalloonStats(stats) => {
http_response(&serde_json::to_string(stats).unwrap(), 200)
}
VmmData::HintingStatus(status) => {
http_response(&serde_json::to_string(status).unwrap(), 200)
}
VmmData::Empty => http_response("", 204),
VmmData::FullVmConfig(cfg) => {
http_response(&serde_json::to_string(cfg).unwrap(), 200)
Expand Down Expand Up @@ -588,6 +606,9 @@ pub mod tests {
swap_out: Some(1),
..Default::default()
}));
verify_ok_response_with(VmmData::HintingStatus(HintingStatus {
..Default::default()
}));
verify_ok_response_with(VmmData::Empty);
verify_ok_response_with(VmmData::FullVmConfig(VmmConfig::default()));
verify_ok_response_with(VmmData::MachineConfiguration(MachineConfig::default()));
Expand Down Expand Up @@ -642,6 +663,18 @@ pub mod tests {
ParsedRequest::try_from(&req).unwrap();
}

#[test]
fn test_try_from_get_balloon_hinting() {
let (mut sender, receiver) = UnixStream::pair().unwrap();
let mut connection = HttpConnection::new(receiver);
sender
.write_all(http_request("GET", "/balloon/hinting/status", None).as_bytes())
.unwrap();
connection.try_read().unwrap();
let req = connection.pop_parsed_request().unwrap();
ParsedRequest::try_from(&req).unwrap();
}

#[test]
fn test_try_from_get_machine_config() {
let (mut sender, receiver) = UnixStream::pair().unwrap();
Expand Down Expand Up @@ -910,13 +943,52 @@ pub mod tests {
connection.try_read().unwrap();
let req = connection.pop_parsed_request().unwrap();
ParsedRequest::try_from(&req).unwrap();

let body = "{ \"stats_polling_interval_s\": 1 }";
sender
.write_all(http_request("PATCH", "/balloon/statistics", Some(body)).as_bytes())
.unwrap();
connection.try_read().unwrap();
let req = connection.pop_parsed_request().unwrap();
ParsedRequest::try_from(&req).unwrap();

let body = "{ \"acknowledge_on_stop\": true }";
sender
.write_all(http_request("PATCH", "/balloon/hinting/start", Some(body)).as_bytes())
.unwrap();
connection.try_read().unwrap();
let req = connection.pop_parsed_request().unwrap();
ParsedRequest::try_from(&req).unwrap();

let body = "{}";
sender
.write_all(http_request("PATCH", "/balloon/hinting/start", Some(body)).as_bytes())
.unwrap();
connection.try_read().unwrap();
let req = connection.pop_parsed_request().unwrap();
ParsedRequest::try_from(&req).unwrap();

sender
.write_all(http_request("PATCH", "/balloon/hinting/start", None).as_bytes())
.unwrap();
connection.try_read().unwrap();
let req = connection.pop_parsed_request().unwrap();
ParsedRequest::try_from(&req).unwrap();

let body = "";
sender
.write_all(http_request("PATCH", "/balloon/hinting/stop", Some(body)).as_bytes())
.unwrap();
connection.try_read().unwrap();
let req = connection.pop_parsed_request().unwrap();
ParsedRequest::try_from(&req).unwrap();

sender
.write_all(http_request("PATCH", "/balloon/hinting/stop", None).as_bytes())
.unwrap();
connection.try_read().unwrap();
let req = connection.pop_parsed_request().unwrap();
ParsedRequest::try_from(&req).unwrap();
}

#[test]
Expand Down
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