From 7ee4e172679029e54f44f096d2e0ec85905c79de Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Fri, 2 Feb 2024 00:22:16 +0100 Subject: log: setlogmask(0) can actually result in a system call, don't use it Before commit 32d07f5e59f2 ("passt, pasta: Completely avoid dynamic memory allocation"), we didn't store the current log mask in a variable, and we fetched it using setlogmask(0) wherever needed. But after that commit, we can use our log_mask copy instead. And we should: with recent glibc versions, setlogmask(0) actually results in a system call, which causes a substantial overhead with high transfer rates: we use setlogmask(0) even to decide we don't want to print debug messages. Now that we rely on log_mask in early stages, before setlogmask() is called, we need to initialise that variable to the special LOG_EMERG mask value right away: define LOG_EARLY to make this clearer, and, while at it, group conditions in vlogmsg() into something more terse. Signed-off-by: Stefano Brivio Reviewed-by: David Gibson --- passt.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'passt.c') diff --git a/passt.c b/passt.c index 44d3a0b..aaa8e58 100644 --- a/passt.c +++ b/passt.c @@ -251,9 +251,6 @@ int main(int argc, char **argv) __openlog(log_name, 0, LOG_DAEMON); - /* Meaning we don't know yet: log everything. LOG_EMERG is unused */ - __setlogmask(LOG_MASK(LOG_EMERG)); - c.epollfd = epoll_create1(EPOLL_CLOEXEC); if (c.epollfd == -1) { perror("epoll_create1"); @@ -322,8 +319,8 @@ int main(int argc, char **argv) if (isolate_prefork(&c)) die("Failed to sandbox process, exiting"); - /* Once the log mask is not LOG_EMERG, we will no longer - * log to stderr if there was a log file specified. + /* Once the log mask is not LOG_EARLY, we will no longer log to stderr + * if there was a log file specified. */ if (c.debug) __setlogmask(LOG_UPTO(LOG_DEBUG)); -- cgit v1.2.3