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[release-1.21] Fix partial cache tail latency by correcting the cache chunk size calc #2177

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Merged
merged 2 commits into from
Sep 24, 2025
+12 −7
Merged

[release-1.21] Fix partial cache tail latency by correcting the cache chunk size calc #2177

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26c608f
Fix partial cache tail latency by correcting the cache chunk size cal…
cemakd Sep 23, 2025
b585ad7
Add unit test to fetchChucnkSizeKiB
cemakd Sep 23, 2025
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6 changes: 3 additions & 3 deletions pkg/gce-pd-csi-driver/cache.go
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Original file line number Diff line number Diff line change
Expand Up @@ -573,9 +573,11 @@ func isCachingSetup(mainLvName string) (error, bool) {
return nil, false
}

// cacheSize is always in GiB
func fetchChunkSizeKiB(cacheSize string) (string, error) {
var chunkSize float64

cacheSize = strings.TrimSuffix(cacheSize, "GiB")
cacheSizeInt, err := strconv.ParseInt(cacheSize, 10, 64)
if err != nil {
return "0", err
Expand Down Expand Up @@ -691,10 +693,8 @@ func addRaidedLSSDToVg(vgName, lssdPath string) error {

func fetchPvSizeGiB() (string, error) {
args := []string{
"--select",
"-o",
"-o", "pv_name,pv_size",
"--noheadings",
"pv_size",
"--units=b",
}
// RAIDed device is always registered with its /dev/md127 equivalent in VG so cannot check it directly based on the RAIDed LSSD path which could be /dev/md/csi-driver-data-cache
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13 changes: 9 additions & 4 deletions pkg/gce-pd-csi-driver/cache_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -13,24 +13,29 @@ func TestFetchChunkSizeKiB(t *testing.T) {
}{
{
name: "chunk size is in the allowed range",
cacheSize: "500",
cacheSize: "500GiB",
expChunkSize: "512KiB", //range defined in fetchChunkSizeKiB
},
{
name: "chunk size is set to the range ceil",
cacheSize: "30000000",
cacheSize: "30000000GiB",
expChunkSize: "1048576KiB", //range defined in fetchChunkSizeKiB - max 1GiB
},
{
name: "chunk size is set to the allowed range floor",
cacheSize: "100",
cacheSize: "100GiB",
expChunkSize: "160KiB", //range defined in fetchChunkSizeKiB - min 160 KiB
},
{
name: "cacheSize set to KiB also sets the chunk size to range floor",
cacheSize: "1",
cacheSize: "1GiB",
expChunkSize: "160KiB", //range defined in fetchChunkSizeKiB - min 160 KiB
},
{
name: "chunk size with GiB string parses correctly",
cacheSize: "375GiB",
expChunkSize: "384KiB",
},
{
name: "invalid cacheSize",
cacheSize: "fdfsdKi",
Expand Down