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efivars: log whenever an EFI variable read access is slow

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This should allow us to detect slowdowns caused by EFI variable read
access a bit.
This commit is contained in:
Lennart Poettering 2020-05-25 17:13:57 +02:00 committed by Zbigniew Jędrzejewski-Szmek
parent 7b11770bae
commit 698564d147
1 changed files with 14 additions and 0 deletions
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14
src/basic/efivars.c
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@ -50,6 +50,7 @@ int efi_get_variable(
_cleanup_free_ char *p = NULL;
_cleanup_free_ void *buf = NULL;
struct stat st;
usec_t begin;
uint32_t a;
ssize_t n;
@ -68,6 +69,9 @@ int efi_get_variable(
return 0;
}
if (DEBUG_LOGGING)
begin = now(CLOCK_MONOTONIC);
fd = open(p, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return log_debug_errno(errno, "open(\"%s\") failed: %m", p);
@ -121,6 +125,16 @@ int efi_get_variable(
/* Assume that the reported size is accurate */
n = st.st_size - 4;
if (DEBUG_LOGGING) {
char ts[FORMAT_TIMESPAN_MAX];
usec_t end;
end = now(CLOCK_MONOTONIC);
if (end > begin + EFI_RETRY_DELAY)
log_debug("Detected slow EFI variable read access on " SD_ID128_FORMAT_STR "-%s: %s",
SD_ID128_FORMAT_VAL(vendor), name, format_timespan(ts, sizeof(ts), end - begin, 1));
}
/* Note that efivarfs interestingly doesn't require ftruncate() to update an existing EFI variable
* with a smaller value. */