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Bump efivarfs_get_variable throughput to 50 variables/second from 33⅓ #259

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Bump efivarfs_get_variable throughput to 50 variables/second from 33⅓ #259

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f6baefa
Remove extraneous and broken self-imposed 20ms sleep (nominally-50/s-…
nabijaczleweli Nov 21, 2023
e371b3f
Bump efivarfs_get_variable throughput to 50 variables/second from 33⅓
nabijaczleweli Nov 21, 2023
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29 changes: 9 additions & 20 deletions src/efivarfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -241,21 +241,10 @@ efivarfs_get_variable(efi_guid_t guid, const char *name, uint8_t **data,
__typeof__(errno) errno_value;
int ret = -1;
size_t size = 0;
uint32_t ret_attributes = 0;
uint8_t *ret_data;
int fd = -1;
char *path = NULL;
int rc;
int ratelimit;

/*
* The kernel rate limiter hits us if we go faster than 100 efi
* variable reads per second as non-root. So if we're not root, just
* delay this long after each read. The user is not going to notice.
*
* 1s / 100 = 10000us.
*/
ratelimit = geteuid() == 0 ? 0 : 10000;

rc = make_efivarfs_path(&path, guid, name);
if (rc < 0) {
Expand All @@ -269,23 +258,23 @@ efivarfs_get_variable(efi_guid_t guid, const char *name, uint8_t **data,
goto err;
}

usleep(ratelimit);
rc = read(fd, &ret_attributes, sizeof (ret_attributes));
rc = read_file(fd, &ret_data, &size);
if (rc < 0) {
efi_error("read failed");
efi_error("read_file failed");
goto err;
}
--size; // read_file pads out 1 extra byte to NUL

usleep(ratelimit);
rc = read_file(fd, &ret_data, &size);
if (rc < 0) {
efi_error("read_file failed");
if (size < sizeof (*attributes)) {
efi_error("no attributes");
goto err;
}

*attributes = ret_attributes;
memcpy(attributes, ret_data, sizeof (*attributes));
memmove(ret_data, ret_data + sizeof (*attributes), size - sizeof (*attributes));

*data = ret_data;
*data_size = size - 1; // read_file pads out 1 extra byte to NUL it */
*data_size = size - sizeof (*attributes);

ret = 0;
err:
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11 changes: 0 additions & 11 deletions src/vars.c
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Original file line number Diff line number Diff line change
Expand Up @@ -290,16 +290,6 @@ vars_get_variable(efi_guid_t guid, const char *name, uint8_t **data,
char *path = NULL;
int rc;
int fd = -1;
int ratelimit;

/*
* The kernel rate limiter hits us if we go faster than 100 efi
* variable reads per second as non-root. So if we're not root, just
* delay this long after each read. The user is not going to notice.
*
* 1s / 100 = 10000us.
*/
ratelimit = geteuid() == 0 ? 0 : 10000;

rc = asprintf(&path, "%s%s-" GUID_FORMAT "/raw_var", get_vars_path(),
name, GUID_FORMAT_ARGS(&guid));
Expand All @@ -314,7 +304,6 @@ vars_get_variable(efi_guid_t guid, const char *name, uint8_t **data,
goto err;
}

usleep(ratelimit);
rc = read_file(fd, &buf, &bufsize);
if (rc < 0) {
efi_error("read_file(%s) failed", path);
Expand Down