On Tue, Apr 29, 2008 at 6:47 AM, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:
> Right now with PIO transfers we can jam the box up horribly as lock IRQs
> off when the transfer is from high memory. We still have other things we
> need to fix in this area to really make a difference but this is the
> buffering side of the fix (the state machine enable/disable irq stuff is
> also needed)
>
> Currently uses kmalloc - which seems to work best, but trivial to
> allocate at init time if wanted
>
> Signed-off-by: Alan Cox <alan@xxxxxxxxxx>
>
> diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-mm1/drivers/ata/libata-sff.c linux-2.6.25-mm1/drivers/ata/libata-sff.c
> --- linux.vanilla-2.6.25-mm1/drivers/ata/libata-sff.c 2008-04-28 11:36:48.000000000 +0100
> +++ linux-2.6.25-mm1/drivers/ata/libata-sff.c 2008-04-28 11:42:05.000000000 +0100
> @@ -665,6 +665,62 @@
> }
>
> /**
> + * ata_bounce_pio_xfer - Transfer a block by PIO from high
> + * @dev: target device
> + * @page: highmem page
> + * @offset: offset in page
> + * @count: bytes to transfer
> + * @do_write: writing if set, reading if not
> + *
> + * Transfer a page of high memory via PIO. Whenever possible use a bounce
> + * buffer to avoid transfers occuring with local IRQ disable
> + */
> +
> +static unsigned int ata_bounce_pio_xfer(struct ata_device *dev, struct page *page,
> + unsigned int offset, int count, int rw)
> +{
> + struct ata_port *ap = dev->link->ap;
> + unsigned long flags;
> + unsigned char *zebedee;
> + unsigned char *buf;
> + unsigned int consumed;
> +
> + BUG_ON(offset + count > PAGE_SIZE);
> +
> + zebedee = kmalloc(count, GFP_ATOMIC);
> + if (likely(zebedee)) {
> + if (rw == WRITE) {
> + local_irq_save(flags);
> + buf = kmap_atomic(page, KM_IRQ0);
> + memcpy(zebedee, buf + offset, count);
> + kunmap_atomic(buf, KM_IRQ0);
> + local_irq_restore(flags);
> + }
> + /* do the actual data transfer */
> + consumed = ap->ops->sff_data_xfer(dev, zebedee, count, rw);
> + if (rw == READ) {
> + /* Read so bounce data upwards */
> + local_irq_save(flags);
> + buf = kmap_atomic(page, KM_IRQ0);
> + memcpy(buf + offset, zebedee, count);
> + kunmap_atomic(buf, KM_IRQ0);
> + local_irq_restore(flags);
> + }
> + kfree(zebedee);
> + } else {
> + /* Only used when we are out of buffer memory
> + as a last last resort */
> + local_irq_save(flags);
> + buf = kmap_atomic(page, KM_IRQ0);
> + /* do the actual data transfer */
> + consumed = ap->ops->sff_data_xfer(dev, buf + offset, count, rw);
> + kunmap_atomic(buf, KM_IRQ0);
> + local_irq_restore(flags);
> + }
> + return consumed;
> +}
> +
> +/**
> * ata_pio_sector - Transfer a sector of data.
> * @qc: Command on going
> *
> @@ -675,7 +731,7 @@
> */
> static void ata_pio_sector(struct ata_queued_cmd *qc)
> {
> - int do_write = (qc->tf.flags & ATA_TFLAG_WRITE);
> + int do_write = (qc->tf.flags & ATA_TFLAG_WRITE) ? WRITE : READ;
> struct ata_port *ap = qc->ap;
> struct page *page;
> unsigned int offset;
> @@ -693,19 +749,9 @@
>
> DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");
>
> - if (PageHighMem(page)) {
> - unsigned long flags;
> -
> - /* FIXME: use a bounce buffer */
> - local_irq_save(flags);
> - buf = kmap_atomic(page, KM_IRQ0);
> -
> - /* do the actual data transfer */
> - ap->ops->sff_data_xfer(qc->dev, buf + offset, qc->sect_size,
> - do_write);
> -
> - kunmap_atomic(buf, KM_IRQ0);
> - local_irq_restore(flags);
> + if (PageHighMem(page) || 1 /* TEST FIXME */) {
Did you want the "|| 1" code committed as well?
thanks,
grant
> + ata_bounce_pio_xfer(qc->dev, page, offset, qc->sect_size,
> + do_write);
> } else {
> buf = page_address(page);
> ap->ops->sff_data_xfer(qc->dev, buf + offset, qc->sect_size,
> @@ -830,19 +876,9 @@
>
> DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");
>
> - if (PageHighMem(page)) {
> - unsigned long flags;
> -
> - /* FIXME: use bounce buffer */
> - local_irq_save(flags);
> - buf = kmap_atomic(page, KM_IRQ0);
> -
> - /* do the actual data transfer */
> - consumed = ap->ops->sff_data_xfer(dev, buf + offset, count, rw);
> -
> - kunmap_atomic(buf, KM_IRQ0);
> - local_irq_restore(flags);
> - } else {
> + if (PageHighMem(page))
> + consumed = ata_bounce_pio_xfer(qc->dev, page, offset, count, rw);
> + else {
> buf = page_address(page);
> consumed = ap->ops->sff_data_xfer(dev, buf + offset, count, rw);
> }
> --
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