From: Jeff Garzik <jeff@garzik.org>
To: Chris Leech <christopher.leech@intel.com>
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH 1/9] ioatdma: Push pending transactions to hardware more frequently
Date: Fri, 02 Mar 2007 22:14:39 -0500 [thread overview]
Message-ID: <45E8E81F.8070805@garzik.org> (raw)
In-Reply-To: <20070303022417.31033.72244.stgit@gitlost.site>
Chris Leech wrote:
> Every 20 descriptors turns out to be to few append commands with
> newer/faster CPUs. Pushing every 4 still cuts down on MMIO writes to an
> acceptable level without letting the DMA engine run out of work.
>
> Signed-off-by: Chris Leech <christopher.leech@intel.com>
> ---
>
> drivers/dma/ioatdma.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/ioatdma.c b/drivers/dma/ioatdma.c
> index 8e87261..0f77a9d 100644
> --- a/drivers/dma/ioatdma.c
> +++ b/drivers/dma/ioatdma.c
> @@ -310,7 +310,7 @@ static dma_cookie_t do_ioat_dma_memcpy(struct ioat_dma_chan *ioat_chan,
> list_splice_init(&new_chain, ioat_chan->used_desc.prev);
>
> ioat_chan->pending += desc_count;
> - if (ioat_chan->pending >= 20) {
> + if (ioat_chan->pending >= 4) {
This sounds like something that will always be wrong -- or in other
words, always be right for only the latest CPUs. Can this be made
dynamic, based on some timing factor?
Jeff
next prev parent reply other threads:[~2007-03-03 3:14 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-03 2:22 [PATCH 0/9] I/OAT fixes Chris Leech
2007-03-03 2:24 ` [PATCH 1/9] ioatdma: Push pending transactions to hardware more frequently Chris Leech
2007-03-03 3:14 ` Jeff Garzik [this message]
2007-03-03 4:27 ` David Miller
2007-03-03 6:00 ` Chris Leech
2007-03-03 2:24 ` [PATCH 2/9] drivers/dma: handle sysfs errors Chris Leech
2007-03-03 2:24 ` [PATCH 3/9] ioatdma: Remove the wrappers around read(bwl)/write(bwl) in ioatdma Chris Leech
2007-03-03 2:24 ` [PATCH 4/9] ioatdma: Remove the use of writeq from the ioatdma driver Chris Leech
2007-03-03 2:24 ` [PATCH 5/9] I/OAT: Add documentation for the tcp_dma_copybreak sysctl Chris Leech
2007-03-03 2:24 ` [PATCH 6/9] I/OAT: Add entries to MAINTAINERS for the DMA memcpy subsystem and ioatdma Chris Leech
2007-03-03 2:24 ` [PATCH 7/9] I/OAT: Only offload copies for TCP when there will be a context switch Chris Leech
2007-03-03 2:24 ` [PATCH 8/9] I/OAT: warning fix Chris Leech
2007-03-03 2:24 ` [PATCH 9/9] I/OAT: fix I/OAT for kexec Chris Leech
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