From 807e40ecc9786755e2f74a7a6a9b20c812588119 Mon Sep 17 00:00:00 2001 From: Mark Salyzyn Date: Thu, 22 Sep 2016 09:56:51 -0700 Subject: liblog: logd: Add android_lookupEventTag_len() Allows us to mitigate the impact of MAP_PRIVATE and copy on write by calling android_lookupEventTag_len instead of android_lookupEventTag, and delaying the copy on write impact to the later. We return a string length in a supplied location along with the string pointer with android_lookupEventTag_len(const EventTagMap* map, size_t* len, int tag). The string is not guaranteed to be nul terminated. Since android_lookupEventTag() called even once can cause the memory impact, we will mark it as deprecated, but we currently have no timeframe for removal since this is a very old interface. Add an API for __android_log_is_loggable_len() that accepts the non null terminated content and fixup callers that would gain because the length is known prior to the call either in the compiler or at runtime. Tackle transition to android_lookupEventTag_len() and fixup callers. On any application that performs logging (eg: com.android.phone) /proc//smaps before: xxxxxxxxxx-xxxxxxxxxx rw-p 00000000 fd:00 463 /system/etc/event-log-tags Size: 20 kB Rss: 20 kB Pss: 1 kB Shared_Clean: 0 kB Shared_Dirty: 20 kB Private_Clean: 0 kB Private_Dirty: 0 kB Referenced: 0 kB Anonymous: 20 kB AnonHugePages: 0 kB Swap: 0 kB SwapPss: 0 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Locked: 0 kB VmFlags: rd wr mr mw me ac /proc//smaps after: xxxxxxxxxx-xxxxxxxxxx rw-p 00000000 fd:00 1773 /system/etc/event-log-tags Size: 20 kB Rss: 20 kB Pss: 1 kB Shared_Clean: 20 kB (was 0kB) Shared_Dirty: 0 kB (was 20kB) Private_Clean: 0 kB Private_Dirty: 0 kB Referenced: 20 kB (was 0kB) Anonymous: 0 kB (was 20kB) AnonHugePages: 0 kB Swap: 0 kB SwapPss: 0 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Locked: 0 kB VmFlags: rd wr mr mw me ac Added liblog-unit-tests --gtest_filter=liblog.event_log_tags to check for Shared_Clean: to not be 0 and Anonymous: to be 0 for all processes referencing event-log-tags. Which can include multiple references to /system/etc/event-log-tags and future possible refs to /data/misc/logd/event-log-tags and /dev/event-log-tags. We want failure messages to help point to errant code using the deprecated interface. This change saves 1/4MB of memory or more on a typical system. Test: gTest liblog-unit-tests Bug: 31456426 Change-Id: I9e08e44d9092bd96fe704b5709242e7195281d33 --- liblog/logd_writer.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'liblog/logd_writer.c') diff --git a/liblog/logd_writer.c b/liblog/logd_writer.c index ebf8b3e46..e8e392d24 100644 --- a/liblog/logd_writer.c +++ b/liblog/logd_writer.c @@ -181,9 +181,9 @@ static int logdWrite(log_id_t logId, struct timespec *ts, } } snapshot = atomic_exchange_explicit(&dropped, 0, memory_order_relaxed); - if (snapshot && __android_log_is_loggable(ANDROID_LOG_INFO, - "liblog", - ANDROID_LOG_VERBOSE)) { + if (snapshot && __android_log_is_loggable_len(ANDROID_LOG_INFO, + "liblog", strlen("liblog"), + ANDROID_LOG_VERBOSE)) { android_log_event_int_t buffer; header.id = LOG_ID_EVENTS; -- cgit v1.2.3