From ac2eb773a50517fbf457130ab2e05ec791b646f1 Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Fri, 21 Jun 2013 06:20:10 +0200 Subject: [PATCH 14/21] ide: convert ide_sector_read() to asynchronous I/O RH-Author: Fam Zheng Message-id: <1371795611-7208-15-git-send-email-famz@redhat.com> Patchwork-id: 52088 O-Subject: [PATCH RHEL-6.5 qemu-kvm v3 14/15] ide: convert ide_sector_read() to asynchronous I/O Bugzilla: 956825 RH-Acked-by: Paolo Bonzini RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Laszlo Ersek From: Stefan Hajnoczi 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 Reviewed-by: Paolo Bonzini Reviewed-by: Zhi Yong Wu Tested-by: Richard Davies Signed-off-by: Kevin Wolf (cherry picked from commit bef0fd5958120542f126f2dedbfce65d8839a94d) Signed-off-by: Fam Zheng Conflicts: hw/ide/core.c --- hw/ide/core.c | 77 ++++++++++++++++++++++++++++++++++++++++--------------- hw/ide/internal.h | 3 +++ 2 files changed, 59 insertions(+), 21 deletions(-) Signed-off-by: Miroslav Rezanina --- hw/ide/core.c | 77 ++++++++++++++++++++++++++++++++++++++-------------- hw/ide/internal.h | 3 ++ 2 files changed, 59 insertions(+), 21 deletions(-) diff --git a/hw/ide/core.c b/hw/ide/core.c index a9df4d8..e8c0267 100644 --- a/hw/ide/core.c +++ b/hw/ide/core.c @@ -378,40 +378,69 @@ static void ide_rw_error(IDEState *s) { ide_set_irq(s->bus); } +static void ide_sector_read(IDEState *s); +static void ide_sector_read_cb(void *opaque, int ret) +{ + IDEState *s = opaque; + int n; + + s->pio_aiocb = NULL; + s->status &= ~BUSY_STAT; + + bdrv_acct_done(s->bs, &s->acct); + if (ret != 0) { + if (ide_handle_rw_error(s, -ret, BM_STATUS_PIO_RETRY | + BM_STATUS_RETRY_READ)) { + return; + } + } + + n = s->nsector; + if (n > s->req_nb_sectors) { + n = s->req_nb_sectors; + } + + /* Allow the guest to read the io_buffer */ + ide_transfer_start(s, s->io_buffer, n * BDRV_SECTOR_SIZE, ide_sector_read); + + ide_set_irq(s->bus); + + ide_set_sector(s, ide_get_sector(s) + n); + s->nsector -= n; +} + static void ide_sector_read(IDEState *s) { int64_t sector_num; - int ret, n; + int n; s->status = READY_STAT | SEEK_STAT; s->error = 0; /* not needed by IDE spec, but needed by Windows */ sector_num = ide_get_sector(s); n = s->nsector; + if (n == 0) { - /* no more sector to read from disk */ ide_transfer_stop(s); - } else { + return; + } + + s->status |= BUSY_STAT; + + if (n > s->req_nb_sectors) { + n = s->req_nb_sectors; + } + #if defined(DEBUG_IDE) - printf("read sector=%" PRId64 "\n", sector_num); + printf("sector=%" PRId64 "\n", sector_num); #endif - if (n > s->req_nb_sectors) - n = s->req_nb_sectors; - bdrv_acct_start(s->bs, &s->acct, n * BDRV_SECTOR_SIZE, BDRV_ACCT_READ); - ret = bdrv_read(s->bs, sector_num, s->io_buffer, n); - bdrv_acct_done(s->bs, &s->acct); - if (ret != 0) { - if (ide_handle_rw_error(s, -ret, - BM_STATUS_PIO_RETRY | BM_STATUS_RETRY_READ)) - { - return; - } - } - ide_transfer_start(s, s->io_buffer, 512 * n, ide_sector_read); - ide_set_irq(s->bus); - ide_set_sector(s, sector_num + n); - s->nsector -= n; - } + s->iov.iov_base = s->io_buffer; + s->iov.iov_len = n * BDRV_SECTOR_SIZE; + qemu_iovec_init_external(&s->qiov, &s->iov, 1); + + bdrv_acct_start(s->bs, &s->acct, n * BDRV_SECTOR_SIZE, BDRV_ACCT_READ); + s->pio_aiocb = bdrv_aio_readv(s->bs, sector_num, &s->qiov, n, + ide_sector_read_cb, s); } @@ -1797,6 +1826,12 @@ static void ide_reset(IDEState *s) #ifdef DEBUG_IDE printf("ide: reset\n"); #endif + + if (s->pio_aiocb) { + bdrv_aio_cancel(s->pio_aiocb); + s->pio_aiocb = NULL; + } + if (s->drive_kind == IDE_CFATA) s->mult_sectors = 0; else diff --git a/hw/ide/internal.h b/hw/ide/internal.h index 83ae6f0..9fdb9d5 100644 --- a/hw/ide/internal.h +++ b/hw/ide/internal.h @@ -435,6 +435,9 @@ 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; -- 1.7.1