diff options
| author | Laurent Vivier <laurent@vivier.eu> | 2010-09-17 18:13:57 +0200 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2010-09-21 15:39:42 +0200 |
| commit | 5fe16888d33af7aca0d613d888c161af68c755c3 (patch) | |
| tree | 1070ab1a9f7499011eb9bef2d6c18cb75d0b1b49 /nbd.c | |
| parent | 581b9e29f36eec5de0779c3dbade980e4405d92e (diff) | |
Improve qemu-nbd performance by 4400 %
This patch allows to reduce the boot time from an NBD server from 225 seconds to
5 seconds (time between the "boot cd:0" and the kernel init) for the
following command lines:
./qemu-nbd -t ../ISO/debian-500-powerpc-netinst.iso
and
./ppc-softmmu/qemu-system-ppc -cdrom nbd:localhost:1024
This patch combines the reply header and payload send operation.
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'nbd.c')
| -rw-r--r-- | nbd.c | 25 |
1 files changed, 18 insertions, 7 deletions
@@ -49,6 +49,7 @@ /* This is all part of the "official" NBD API */ +#define NBD_REPLY_SIZE (4 + 4 + 8) #define NBD_REQUEST_MAGIC 0x25609513 #define NBD_REPLY_MAGIC 0x67446698 @@ -588,7 +589,7 @@ static int nbd_receive_request(int csock, struct nbd_request *request) int nbd_receive_reply(int csock, struct nbd_reply *reply) { - uint8_t buf[4 + 4 + 8]; + uint8_t buf[NBD_REPLY_SIZE]; uint32_t magic; memset(buf, 0xAA, sizeof(buf)); @@ -655,9 +656,9 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size, uint64_t dev_offset, if (nbd_receive_request(csock, &request) == -1) return -1; - if (request.len > data_size) { + if (request.len + NBD_REPLY_SIZE > data_size) { LOG("len (%u) is larger than max len (%u)", - request.len, data_size); + request.len + NBD_REPLY_SIZE, data_size); errno = EINVAL; return -1; } @@ -687,7 +688,8 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size, uint64_t dev_offset, case NBD_CMD_READ: TRACE("Request type is READ"); - if (bdrv_read(bs, (request.from + dev_offset) / 512, data, + if (bdrv_read(bs, (request.from + dev_offset) / 512, + data + NBD_REPLY_SIZE, request.len / 512) == -1) { LOG("reading from file failed"); errno = EINVAL; @@ -697,12 +699,21 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size, uint64_t dev_offset, TRACE("Read %u byte(s)", request.len); - if (nbd_send_reply(csock, &reply) == -1) - return -1; + /* Reply + [ 0 .. 3] magic (NBD_REPLY_MAGIC) + [ 4 .. 7] error (0 == no error) + [ 7 .. 15] handle + */ + + cpu_to_be32w((uint32_t*)data, NBD_REPLY_MAGIC); + cpu_to_be32w((uint32_t*)(data + 4), reply.error); + cpu_to_be64w((uint64_t*)(data + 8), reply.handle); TRACE("Sending data to client"); - if (write_sync(csock, data, request.len) != request.len) { + if (write_sync(csock, data, + request.len + NBD_REPLY_SIZE) != + request.len + NBD_REPLY_SIZE) { LOG("writing to socket failed"); errno = EINVAL; return -1; |