The 'nvme_map_sgl' method has a 256 element array used for copying
data from the device. Skip the automatic zero-init of this array
to eliminate the performance overhead in the I/O hot path.
The 'segment' array will be fully initialized when reading data from
the device.
The 'nme_changed_nslist' method has a 4k byte array that is manually
initialized with memset(). The compiler ought to be intelligent
enough to turn the memset() into a static initialization operation,
and thus not duplicate the automatic zero-init. Replacing memset()
with '{}' makes it unambiguous that the array is statically initialized.
Signed-off-by: Daniel P. Berrangé <berra...@redhat.com>
---
hw/nvme/ctrl.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index fd935507bc..220002830d 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -1057,7 +1057,8 @@ static uint16_t nvme_map_sgl(NvmeCtrl *n, NvmeSg *sg,
NvmeSglDescriptor sgl,
*/
#define SEG_CHUNK_SIZE 256
- NvmeSglDescriptor segment[SEG_CHUNK_SIZE], *sgld, *last_sgld;
+ QEMU_UNINITIALIZED NvmeSglDescriptor segment[SEG_CHUNK_SIZE];
+ NvmeSglDescriptor *sgld, *last_sgld;
uint64_t nsgld;
uint32_t seg_len;
uint16_t status;
@@ -5128,7 +5129,7 @@ static uint16_t nvme_error_info(NvmeCtrl *n, uint8_t rae,
uint32_t buf_len,
static uint16_t nvme_changed_nslist(NvmeCtrl *n, uint8_t rae, uint32_t buf_len,
uint64_t off, NvmeRequest *req)
{
- uint32_t nslist[1024];
+ uint32_t nslist[1024] = {};
uint32_t trans_len;
int i = 0;
uint32_t nsid;
@@ -5138,7 +5139,6 @@ static uint16_t nvme_changed_nslist(NvmeCtrl *n, uint8_t
rae, uint32_t buf_len,
return NVME_INVALID_FIELD | NVME_DNR;
}
- memset(nslist, 0x0, sizeof(nslist));
trans_len = MIN(sizeof(nslist) - off, buf_len);
while ((nsid = find_first_bit(n->changed_nsids, NVME_CHANGED_NSID_SIZE)) !=
--
2.49.0
