Hello,
On 04/14/2010 09:46 AM, Grant Grundler wrote:
> In 2009, While running "cache read" performance test of drives behind
> SII PMP we encountered a "all 5 drives" timeout on more than 30% of the
> machines under test. This patch reduces the rate by a factor of about 70.
> Low enough that we didn't care to further investigate the issue.
Interesting.
> Performance impact with any sort of "normal" use was ~2%+ CPU and less
> than 1% throughput degradation. Worst case impact (cached read) was
> 6% IOPS reduction. This is with NCQ off (q=1) but I believe FIS based
> switching enabled in the SATA driver.
Given the general flakiness of the device, I'm more than willing to
pay some overhead for stability and the performance hit seems pretty
small.
> @@ -260,12 +262,28 @@ static int sata_pmp_configure(struct ata_device
> *dev, int print_info)
> goto fail;
> }
>
> + /* For Sil3726, disable sending Early R_OK */
> + if (vendor == 0x1095 && devid == 0x3726) {
Isn't this also applicable to 4723 and 4726?
> diff --git a/include/linux/ata.h b/include/linux/ata.h
> index 700c5b9..18fc208 100644
> --- a/include/linux/ata.h
> +++ b/include/linux/ata.h
> @@ -386,6 +386,7 @@ enum {
> SATA_PMP_GSCR_ERROR_EN = 33,
> SATA_PMP_GSCR_FEAT = 64,
> SATA_PMP_GSCR_FEAT_EN = 96,
> + SATA_PMP_GSCR_SII_POL = 129, /* VENDOR : Silicon Image 3726/4726 */
Can you plesae define it inside libata-pmp.c? ata.h only contains
stuff defined by the ATA standard.
Other than the above nitpicks,
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Thanks.
--
tejun
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