Enable dynamic read logs buffer sizing for incfs
Default buffer size of 4 pages causes many missed log records
because of ring buffer overflows. This change adds a dynamic
sizing, up to 32 pages, that has shown to decrease dropped
records pretty much to nil
Fallback code automatically decreases the buffer size in case
of kernel memory fragmentation - some logs are still much
better than no logs at all
Bug: 203551890
Test: manual, adb install <Apk>; checked for fallback by
increasing max size to 1024 pages
Change-Id: I0ea46c1ad2534b1dbb5faaead52afab88b66747b
diff --git a/VoldNativeService.cpp b/VoldNativeService.cpp
index b4b9276..291a0d9 100644
--- a/VoldNativeService.cpp
+++ b/VoldNativeService.cpp
@@ -1039,16 +1039,30 @@
};
auto cleanup =
std::unique_ptr<incfs::Control, decltype(cleanupFunc)>(&incfsControl, cleanupFunc);
- if (auto error = incfs::setOptions(
- incfsControl,
- {.defaultReadTimeoutMs =
- enableReadTimeouts ? INCFS_DEFAULT_READ_TIMEOUT_MS : kIncFsReadNoTimeoutMs,
- .readLogBufferPages = enableReadLogs ? INCFS_DEFAULT_PAGE_READ_BUFFER_PAGES : 0,
- .sysfsName = sysfsName.c_str()});
- error < 0) {
- return binder::Status::fromServiceSpecificError(error);
- }
+ constexpr auto minReadLogBufferPages = INCFS_DEFAULT_PAGE_READ_BUFFER_PAGES;
+ constexpr auto maxReadLogBufferPages = 8 * INCFS_DEFAULT_PAGE_READ_BUFFER_PAGES;
+ auto options = incfs::MountOptions{
+ .defaultReadTimeoutMs =
+ enableReadTimeouts ? INCFS_DEFAULT_READ_TIMEOUT_MS : kIncFsReadNoTimeoutMs,
+ .readLogBufferPages = enableReadLogs ? maxReadLogBufferPages : 0,
+ .sysfsName = sysfsName.c_str()};
+
+ for (;;) {
+ const auto error = incfs::setOptions(incfsControl, options);
+ if (!error) {
+ return Ok();
+ }
+ if (!enableReadLogs || error != -ENOMEM) {
+ return binder::Status::fromServiceSpecificError(error);
+ }
+ // In case of memory allocation error retry with a smaller buffer.
+ options.readLogBufferPages /= 2;
+ if (options.readLogBufferPages < minReadLogBufferPages) {
+ return binder::Status::fromServiceSpecificError(error);
+ }
+ }
+ // unreachable, but makes the compiler happy
return Ok();
}