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fastbootd: use O_DIRECT for write partition

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Direct writes for partition flashing significantly increase performance.
Use O_DIRECT flag when opening partition for flashing. Additionally use
a 4096b aligned buffer which is required for O_DIRECT.
Switch from using 8MB write buffer to 1MB write buffer, as the extra
allocation has no performance impact.

Test: flash locally and reach home screen
Bug: 205151372
Signed-off-by: Konstantin Vyshetsky <vkon@google.com>
Change-Id: I060f438cf698d0fda1e59e35338bb5dc1cd05b51
This commit is contained in:
Konstantin Vyshetsky 2021-11-04 10:27:06 -07:00
parent 81cc119eff
commit d5f3da8dc5
1 changed files with 15 additions and 3 deletions
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18
fastboot/device/flashing.cpp
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@ -16,6 +16,7 @@
#include "flashing.h"
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
@ -77,9 +78,20 @@ void WipeOverlayfsForPartition(FastbootDevice* device, const std::string& partit
int FlashRawDataChunk(int fd, const char* data, size_t len) {
size_t ret = 0;
const size_t max_write_size = 1048576;
void* aligned_buffer;
if (posix_memalign(&aligned_buffer, 4096, max_write_size)) {
PLOG(ERROR) << "Failed to allocate write buffer";
return -ENOMEM;
}
auto aligned_buffer_unique_ptr = std::unique_ptr<void, decltype(&free)>{aligned_buffer, free};
while (ret < len) {
int this_len = std::min(static_cast<size_t>(1048576UL * 8), len - ret);
int this_ret = write(fd, data, this_len);
int this_len = std::min(max_write_size, len - ret);
memcpy(aligned_buffer_unique_ptr.get(), data, this_len);
int this_ret = write(fd, aligned_buffer_unique_ptr.get(), this_len);
if (this_ret < 0) {
PLOG(ERROR) << "Failed to flash data of len " << len;
return -1;
@ -147,7 +159,7 @@ static void CopyAVBFooter(std::vector<char>* data, const uint64_t block_device_s
int Flash(FastbootDevice* device, const std::string& partition_name) {
PartitionHandle handle;
if (!OpenPartition(device, partition_name, &handle)) {
if (!OpenPartition(device, partition_name, &handle, O_WRONLY | O_DIRECT)) {
return -ENOENT;
}