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Clarify rate-limiting further

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This commit is contained in:
Alfonso Acosta
2016-02-08 12:45:48 +00:00
parent ccabaf5e6a
commit 08969ec154
2 changed files with 14 additions and 13 deletions
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25
probe/endpoint/procspy/background_reader_linux.go
View File

@@ -13,10 +13,11 @@ import (
)
const (
initialRateLimit = 50 * time.Millisecond // Read 20 * fdBlockSize file descriptors (/proc/PID/fd/*) per namespace per second
maxRateLimit = 250 * time.Millisecond // Read at least 4 * fdBlockSize file descriptors per namespace per second
fdBlockSize = uint64(300)
targetWalkTime = 10 * time.Second // Aim at walking all files in 10 seconds
initialRateLimitPeriod = 50 * time.Millisecond // Read 20 * fdBlockSize file descriptors (/proc/PID/fd/*) per namespace per second
maxRateLimitPeriod = 250 * time.Millisecond // Read at least 4 * fdBlockSize file descriptors per namespace per second
fdBlockSize = uint64(300) // Maximum number of /proc/PID/fd/* files to stat per rate-limit period
// (as a rule of thumb going through each block should be more expensive than reading /proc/PID/tcp{,6})
targetWalkTime = 10 * time.Second // Aim at walking all files in 10 seconds
)
type backgroundReader struct {
@@ -63,12 +64,12 @@ func (br *backgroundReader) stop() error {
func (br *backgroundReader) loop() {
const (
maxRateLimitF = float64(maxRateLimit)
targetWalkTimeF = float64(targetWalkTime)
maxRateLimitPeriodF = float64(maxRateLimitPeriod)
targetWalkTimeF = float64(targetWalkTime)
)
rateLimit := initialRateLimit
ticker := time.NewTicker(rateLimit)
rateLimitPeriod := initialRateLimitPeriod
ticker := time.NewTicker(rateLimitPeriod)
for {
start := time.Now()
sockets, err := walkProcPid(br.walkingBuf, br.walker, ticker.C, fdBlockSize)
@@ -107,12 +108,12 @@ func (br *backgroundReader) loop() {
}
// Adjust rate limit to more-accurately meet the target walk time in next iteration
scaledRateLimit := targetWalkTimeF / walkTimeF * float64(rateLimit)
rateLimit = time.Duration(math.Min(scaledRateLimit, maxRateLimitF))
log.Debugf("background /proc reader: new rate limit %s", rateLimit)
scaledRateLimitPeriod := targetWalkTimeF / walkTimeF * float64(rateLimitPeriod)
rateLimitPeriod = time.Duration(math.Min(scaledRateLimitPeriod, maxRateLimitPeriodF))
log.Debugf("background /proc reader: new rate limit %s", rateLimitPeriod)
ticker.Stop()
ticker = time.NewTicker(rateLimit)
ticker = time.NewTicker(rateLimitPeriod)
br.walkingBuf.Reset()

2
probe/endpoint/procspy/proc_internal_test.go
View File

@@ -61,7 +61,7 @@ func TestWalkProcPid(t *testing.T) {
walker := process.NewWalker(procRoot)
ticker := time.NewTicker(time.Millisecond)
defer ticker.Stop()
fdBlockSize := 1
fdBlockSize := uint64(1)
have, err := walkProcPid(&buf, walker, ticker.C, fdBlockSize)
if err != nil {
t.Fatal(err)