Delay writing PIO output until io_buffer is filled or ATA command
completion, rather than when interrupts are generated. As an example
of the new behavior, issuing WRITE SECTOR(S) with a sector count of
256 will result in only a single call to blk_aio_pwritev rather than
after each of the 256 sectors are transferred. Up to a 50% increase
in PIO throughput can be achieved thanks to the reduction in system
call overhead and writing larger blocks (up to 128 KiB, with the size
limited by IDE_DMA_BUF_SECTORS).
Signed-off-by: Lev Kujawski <lku...@member.fsf.org>
---
hw/ide/core.c | 62 ++++++++++++++++++++++++---------------
include/hw/ide/internal.h | 1 +
2 files changed, 39 insertions(+), 24 deletions(-)
diff --git a/hw/ide/core.c b/hw/ide/core.c
index 5a24547e49..b178584bc3 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1025,23 +1025,20 @@ static void ide_sector_write_cb(void *opaque, int ret)
block_acct_done(blk_get_stats(s->blk), &s->acct);
- n = s->nsector;
- if (n > s->req_nb_sectors) {
- n = s->req_nb_sectors;
- }
- s->nsector -= n;
-
+ n = (s->data_end - s->io_buffer) >> BDRV_SECTOR_BITS;
ide_set_sector(s, ide_get_sector(s) + n);
+ n %= s->req_nb_sectors;
+ s->nsector -= n ? n : s->req_nb_sectors;
+
if (s->nsector == 0) {
/* no more sectors to write */
ide_transfer_stop(s);
} else {
- int n1 = s->nsector;
- if (n1 > s->req_nb_sectors) {
- n1 = s->req_nb_sectors;
- }
- ide_transfer_start(s, s->io_buffer, n1 * BDRV_SECTOR_SIZE,
- ide_sector_write);
+ const int n1 =
+ (MIN(IDE_DMA_BUF_SECTORS, s->nsector)) << BDRV_SECTOR_BITS;
+ s->octets_until_irq =
+ (MIN(s->nsector, s->req_nb_sectors)) << BDRV_SECTOR_BITS;
+ ide_transfer_start(s, s->io_buffer, n1, ide_sector_write);
}
if (win2k_install_hack && ((++s->irq_count % 16) == 0)) {
@@ -1063,14 +1060,21 @@ static void ide_sector_write(IDEState *s)
int64_t sector_num;
int n;
- s->status = READY_STAT | SEEK_STAT | BUSY_STAT;
- sector_num = ide_get_sector(s);
+ assert(s->octets_until_irq == 0);
- n = s->nsector;
- if (n > s->req_nb_sectors) {
- n = s->req_nb_sectors;
+ if (s->data_ptr < s->data_end) {
+ s->nsector -= s->req_nb_sectors;
+ s->octets_until_irq =
+ (MIN(s->nsector, s->req_nb_sectors)) << BDRV_SECTOR_BITS;
+ s->status = READY_STAT | SEEK_STAT | DRQ_STAT;
+ ide_set_irq(s->bus);
+ return;
}
+ s->status = READY_STAT | SEEK_STAT | BUSY_STAT;
+ sector_num = ide_get_sector(s);
+ n = (s->data_end - s->io_buffer) >> BDRV_SECTOR_BITS;
+
trace_ide_sector_write(sector_num, n);
if (!ide_sect_range_ok(s, sector_num, n)) {
@@ -1378,6 +1382,7 @@ static void ide_reset(IDEState *s)
/* ATA DMA state */
s->io_buffer_size = 0;
s->req_nb_sectors = 0;
+ s->octets_until_irq = 0;
ide_set_signature(s);
/* init the transfer handler so that 0xffff is returned on data
@@ -1500,10 +1505,11 @@ static bool cmd_write_multiple(IDEState *s, uint8_t cmd)
ide_cmd_lba48_transform(s, lba48);
s->req_nb_sectors = s->mult_sectors;
- n = MIN(s->nsector, s->req_nb_sectors);
-
+ n = (MIN(IDE_DMA_BUF_SECTORS, s->nsector)) << BDRV_SECTOR_BITS;
+ s->octets_until_irq =
+ (MIN(s->nsector, s->req_nb_sectors)) << BDRV_SECTOR_BITS;
s->status = SEEK_STAT | READY_STAT;
- ide_transfer_start(s, s->io_buffer, 512 * n, ide_sector_write);
+ ide_transfer_start(s, s->io_buffer, n, ide_sector_write);
s->media_changed = 1;
@@ -1535,6 +1541,7 @@ static bool cmd_read_pio(IDEState *s, uint8_t cmd)
static bool cmd_write_pio(IDEState *s, uint8_t cmd)
{
bool lba48 = (cmd == WIN_WRITE_EXT);
+ int n;
if (!s->blk) {
ide_abort_command(s);
@@ -1544,8 +1551,10 @@ static bool cmd_write_pio(IDEState *s, uint8_t cmd)
ide_cmd_lba48_transform(s, lba48);
s->req_nb_sectors = 1;
+ n = (MIN(IDE_DMA_BUF_SECTORS, s->nsector)) << BDRV_SECTOR_BITS;
+ s->octets_until_irq = BDRV_SECTOR_SIZE;
s->status = SEEK_STAT | READY_STAT;
- ide_transfer_start(s, s->io_buffer, 512, ide_sector_write);
+ ide_transfer_start(s, s->io_buffer, n, ide_sector_write);
s->media_changed = 1;
@@ -1699,7 +1708,7 @@ static bool cmd_identify_packet(IDEState *s, uint8_t cmd)
{
ide_atapi_identify(s);
s->status = READY_STAT | SEEK_STAT;
- ide_transfer_start(s, s->io_buffer, 512, ide_transfer_stop);
+ ide_transfer_start(s, s->io_buffer, BDRV_SECTOR_SIZE, ide_transfer_stop);
ide_set_irq(s->bus);
return false;
}
@@ -1745,6 +1754,7 @@ static bool cmd_packet(IDEState *s, uint8_t cmd)
s->dma_cmd = IDE_DMA_ATAPI;
}
s->nsector = 1;
+ s->octets_until_irq = ATAPI_PACKET_SIZE;
ide_transfer_start(s, s->io_buffer, ATAPI_PACKET_SIZE,
ide_atapi_cmd);
return false;
@@ -2358,7 +2368,9 @@ void ide_data_writew(void *opaque, uint32_t addr,
uint32_t val)
*(uint16_t *)p = le16_to_cpu(val);
p += 2;
s->data_ptr = p;
- if (p >= s->data_end) {
+ s->octets_until_irq -= 2;
+
+ if (s->octets_until_irq == 0) {
s->status &= ~DRQ_STAT;
s->end_transfer_func(s);
}
@@ -2416,7 +2428,9 @@ void ide_data_writel(void *opaque, uint32_t addr,
uint32_t val)
*(uint32_t *)p = le32_to_cpu(val);
p += 4;
s->data_ptr = p;
- if (p >= s->data_end) {
+ s->octets_until_irq -= 4;
+
+ if (s->octets_until_irq == 0) {
s->status &= ~DRQ_STAT;
s->end_transfer_func(s);
}
diff --git a/include/hw/ide/internal.h b/include/hw/ide/internal.h
index 97e7e59dc5..3f79fbaf32 100644
--- a/include/hw/ide/internal.h
+++ b/include/hw/ide/internal.h
@@ -428,6 +428,7 @@ struct IDEState {
QEMUSGList sg;
/* PIO transfer handling */
int req_nb_sectors; /* number of sectors per interrupt */
+ int octets_until_irq;
EndTransferFunc *end_transfer_func;
uint8_t *data_ptr;
uint8_t *data_end;
--
2.34.1
