Prev: e1000e crashes with 2.6.34.x and ThinkPad T60
Next: GIC: Dont disable INT in ack callback
From: Jens Axboe on 24 Jul 2010 06:10
On 07/24/2010 10:04 AM, Heinz Diehl wrote:
> On 14.07.2010, Jeff Moyer wrote:
>
>> Comments, as always, are welcome.
>
> This patch, applied to 2.6.35-rc6, increases desktop interactivity
> _NOTICEABLY_ on my quadcore machine, and the machine stays rock-stable.
> I have now tested this patch with the latest 2.6.35-rc kernels over
> 1 week.
>
> Unfortunately, I can't provide some testing results which makes this
> statement more objective, but I'll do some synthetic testing in the next
> days.

It is extremely unlikely that this patch will have any impact on
"normal" workloads. To even hit a code path where it would make a
difference, you would need to use O_DIRECT IO, otherwise you cannot have
aliases in the IO scheduler.

--
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
From: Jens Axboe on 2 Aug 2010 08:00
On 2010-07-26 15:17, Jeff Moyer wrote:
> Jens Axboe <axboe(a)kernel.dk> writes:
>
>> On 07/24/2010 10:04 AM, Heinz Diehl wrote:
>>> On 14.07.2010, Jeff Moyer wrote:
>>>
>>>> Comments, as always, are welcome.
>>>
>>> This patch, applied to 2.6.35-rc6, increases desktop interactivity
>>> _NOTICEABLY_ on my quadcore machine, and the machine stays rock-stable.
>>> I have now tested this patch with the latest 2.6.35-rc kernels over
>>> 1 week.
>>>
>>> Unfortunately, I can't provide some testing results which makes this
>>> statement more objective, but I'll do some synthetic testing in the next
>>> days.
>>
>> It is extremely unlikely that this patch will have any impact on
>> "normal" workloads. To even hit a code path where it would make a
>> difference, you would need to use O_DIRECT IO, otherwise you cannot have
>> aliases in the IO scheduler.
>
> I agree that it shouldn't help normal workloads at all. I do think
> there is one other case where you can get aliases: doing I/O both
> through the file system and the underlying device. However, that's
> obviously a bad idea (and maybe open_bdev_exclusive will keep that from
> happening?).

That's correct, you could construct such a test case since you would
get page cache synchronization from different mappings. But again,
not something that the casual user would run into :-)

Exclusive opens only guard against each other, not against "normal"
opens.

--
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: e1000e crashes with 2.6.34.x and ThinkPad T60
Next: GIC: Dont disable INT in ack callback