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Date:      Thu, 4 Mar 1999 00:40:54 +0100 (MET)
From:      "D. Rock" <rock@wurzelausix.CS.Uni-SB.DE>
To:        freebsd-current@FreeBSD.ORG
Subject:   Re: ata1: unwanted interrupt
Message-ID:  <199903032340.AAA06675@vodix.aremorika>

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> >    After having CVSupped to the latest 4.0-CURRENT tree
> > (just now), I noticed the amazing speed of the new ATA driver.
> 
> The amazing speed of the new ATA driver? Were you using 32 bit transfers
> and multi-sector IO with the older driver?
> 
> I assumed from the benchmarks posted that I had no reason to feel
> alarmed about the fact that the new driver offered no tangible
> performance increase.
> 
> My understanding was that we'd "feel it" when DMA transfers were enabled
> for those drives that support them.
I also tried the new ata code and wasn't impressed by the speed:
With the old driver I achieved 12 MB/s with almost no CPU load on my
ST34321A drive. The new driver works flawless in my configuration
(I only have a single IDE drive attached, the rest is SCSI. Chipset is
Ali Aladdin), but I only get about 7MB/s from the drive while having
70% irq load.

(I have done the tests with dd from the raw device and a block size of
1MB)

So I didn't notice any problems with the new code, but we'll have to wait
until DMA is supported to get a really decent performance.

Just to be complete. Here are the relevant portions of dmesg output
for just another working configuration:

ata-pci0: <Acer Aladdin IV/V IDE controller> rev 0xc1 int a irq 0 on pci0.15.0
ata0 at 0x01f0 irq 14 on ata-pci0
[...]
ad0: <ST34321A/3.29> ATA-4 disk at ata0 as master
ad0: 4103MB (8404830 sectors), 8894 cyls, 15 heads, 63 S/T, 512 B/S
ad0: 16 secs/int, 0 depth queue 


Daniel


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