From: Jeff Garzik <jeff@garzik.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>, Mark Lord <liml@rtr.ca>
Cc: Tejun Heo <htejun@gmail.com>, linux-ide@vger.kernel.org
Subject: Re: Polling (was Re: [PATCHSET 2/2] implement PMP support, take 6)
Date: Fri, 28 Sep 2007 21:43:53 -0400 [thread overview]
Message-ID: <46FDADD9.9050007@garzik.org> (raw)
In-Reply-To: <20070928220309.7c9ed816@the-village.bc.nu>
Alan Cox wrote:
>> Jeff, seeing as Tejun's commitment is never in doubt here,
>> I really believe we should go with the existing PMP patchset
>> for 2.6.24 (unless the respin happens quickly enough).
>>
>> This functionality is way overdue, and we shouldn't be impeding it
>> as long as we have been.
>
> I would second this. Its far too important to not get this stuff upstream
> and usable NOW. Yes the model will have to change a bit but the entire
> libata today has almost no resemblence to the one a year ago.
>
> It can evolve and then the old one can die off just as we did with EH
> (except for libsas anyway)
I certainly deserve plenty of blame for not catching this fact earlier,
much to my chagrin. But there are real technical issues at hand:
Polling ALREADY makes the job of fixing SAS/SATA exception handling
difficult. Expanding polling to something SAS/SATA controllers treat as
fundamentally irq-driven and integrated with the rest of the command
flow is moving in the wrong direction.
To re-re-re-summarize, polling in PMP is fundamentally broken for an
ENTIRE CLASS OF HARDWARE that we actively support today. And
jgarzik/misc-2.6.git#sas is adding two more controllers to that list.
Jeff
next prev parent reply other threads:[~2007-09-29 1:43 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-23 4:19 [PATCHSET 2/2] implement PMP support, take 6 Tejun Heo
2007-09-23 4:19 ` [PATCH 01/10] libata-pmp: update ata_eh_reset() for PMP Tejun Heo
2007-09-23 4:19 ` [PATCH 03/10] libata-pmp: hook PMP support and enable it Tejun Heo
2007-09-23 4:19 ` [PATCH 08/10] ahci: implement PMP support Tejun Heo
2007-09-23 4:19 ` [PATCH 07/10] sata_sil24: implement PORT_RST Tejun Heo
2007-09-23 4:19 ` [PATCH 02/10] libata-pmp: implement Port Multiplier support Tejun Heo
2007-09-23 4:19 ` [PATCH 04/10] libata-pmp: extend ACPI support to cover PMP Tejun Heo
2007-09-23 4:19 ` [PATCH 05/10] libata-pmp: implement qc_defer for command switching PMP support Tejun Heo
2007-09-23 4:19 ` [PATCH 06/10] sata_sil24: implement " Tejun Heo
2007-09-23 4:19 ` [PATCH 10/10] ahci: implement AHCI_HFLAG_NO_PMP Tejun Heo
2007-09-23 4:19 ` [PATCH 09/10] ahci: move host flags over to pi.private_data Tejun Heo
2007-09-26 2:09 ` Polling (was Re: [PATCHSET 2/2] implement PMP support, take 6) Jeff Garzik
2007-09-26 2:12 ` Jeff Garzik
2007-09-26 8:41 ` Tejun Heo
2007-09-28 12:10 ` Tejun Heo
2007-09-28 13:54 ` Jeff Garzik
2007-09-28 14:18 ` Tejun Heo
2007-09-28 14:57 ` Alan Cox
2007-09-28 15:20 ` Jeff Garzik
2007-09-28 15:43 ` Alan Cox
2007-09-28 15:40 ` Jeff Garzik
2007-09-28 20:00 ` Mark Lord
2007-09-29 1:49 ` Jeff Garzik
2007-09-29 3:29 ` Jeff Garzik
2007-09-29 4:58 ` Andrew Morton
2007-09-29 5:09 ` Jeff Garzik
2007-09-29 16:51 ` Greg Freemyer
2007-09-29 20:56 ` Alan Cox
2007-10-01 12:28 ` Jeff Garzik
2007-09-28 15:22 ` Jeff Garzik
2007-09-28 16:48 ` Tejun Heo
2007-09-28 20:02 ` Mark Lord
2007-09-28 20:25 ` Bartlomiej Zolnierkiewicz
2007-09-28 21:03 ` Alan Cox
2007-09-29 1:43 ` Jeff Garzik [this message]
2007-09-29 5:24 ` Tejun Heo
2007-10-01 13:31 ` Jeff Garzik
2007-10-02 0:11 ` Tejun Heo
2007-10-02 14:25 ` Alan Cox
2007-10-02 14:30 ` Jeff Garzik
2007-09-29 12:32 ` Mark Lord
2007-10-01 12:38 ` Jeff Garzik
2007-10-02 0:12 ` Tejun Heo
2007-10-02 12:56 ` Jeff Garzik
2007-10-02 13:06 ` Mark Lord
2007-10-02 13:30 ` Jeff Garzik
2007-10-06 22:02 ` Tejun Heo
2007-10-09 2:09 ` Jeff Garzik
2007-10-09 6:54 ` Tejun Heo
2007-09-28 14:20 ` Mark Lord
2007-09-28 15:36 ` Jeff Garzik
2007-09-28 15:55 ` Alan Cox
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