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Groups > linux.kernel > #1296734
| From | One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v3 66/77] ncr5380: Fix soft lockups |
| Date | 2015-12-22 12:50 +0100 |
| Message-ID | <qItC1-3qD-1@gated-at.bofh.it> (permalink) |
| References | <qIl1L-6kS-3@gated-at.bofh.it> <qIlbt-6oO-41@gated-at.bofh.it> |
| Organization | Intel Corporation |
On Tue, 22 Dec 2015 12:18:44 +1100 Finn Thain <fthain@telegraphics.com.au> wrote: > Because of the rudimentary design of the chip, it is necessary to poll the > SCSI bus signals during PIO and this tends to hog the CPU. The driver will > accept new commands while others execute, and this causes a soft lockup > because the workqueue item will not terminate until the issue queue is > emptied. > > When exercising dmx3191d using sequential IO from dd, the driver is sent > 512 KiB WRITE commands and 128 KiB READs. For a PIO transfer, the rate is > is only about 300 KiB/s, so these are long-running commands. And although > PDMA may run at several MiB/s, interrupts are disabled for the duration > of the transfer. > > Fix the unresponsiveness and soft lockup issues by calling cond_resched() > after each command is completed and by limiting max_sectors for drivers > that don't implement real DMA. Is there a reason for not doing some limiting in the DMA case too. A 512K write command even with DMA on a low end 68K box introduces a second of latency before another I/O can be scheduled ? Alan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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[PATCH v3 66/77] ncr5380: Fix soft lockups Finn Thain <fthain@telegraphics.com.au> - 2015-12-22 03:50 +0100
Re: [PATCH v3 66/77] ncr5380: Fix soft lockups One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2015-12-22 12:50 +0100
Re: [PATCH v3 66/77] ncr5380: Fix soft lockups Finn Thain <fthain@telegraphics.com.au> - 2015-12-22 14:50 +0100
Re: [PATCH v3 66/77] ncr5380: Fix soft lockups Michael Schmitz <schmitzmic@gmail.com> - 2015-12-23 01:50 +0100
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