motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-05 00:33:55 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

ide: convert ide_sector_read() to asynchronous I/O

Browse source 
The IDE PIO interface currently uses bdrv_read() to perform reads
synchronously.  Synchronous I/O in the vcpu thread is bad because it
prevents the guest from executing code - it makes the guest
unresponsive.

This patch converts IDE PIO to use bdrv_aio_readv().  We simply need to
use the BUSY_STAT status so the guest knows to wait while we are busy.

The only external user of ide_sector_read() is restart behavior on I/O
errors and it is not affected by this change.  We still need to restart
I/O in the same way.

Migration is also unaffected if I understand the code correctly.  We
continue to use the same transfer function and the BUSY_STAT status
should never be migrated since we flush I/O before migrating device
state.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Tested-by: Richard Davies <richard@arachsys.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2012-03-29 10:31:30 +01:00 • committed by Kevin Wolf
parent 592fa07043
commit bef0fd5958
2 changed files with 61 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

3
hw/ide/internal.h
View file

@ -385,6 +385,9 @@ struct IDEState {
int cd_sector_size;
int atapi_dma; /* true if dma is requested for the packet cmd */
BlockAcctCookie acct;
BlockDriverAIOCB *pio_aiocb;
struct iovec iov;
QEMUIOVector qiov;
/* ATA DMA state */
int io_buffer_size;
QEMUSGList sg;