Re: [PATCH] mm: moving dirty pages balancing to pdfludh entirely

From: Antonio Vargas
Date: Mon Jul 03 2006 - 13:30:24 EST


On 6/28/06, Nikita Danilov <nikita@xxxxxxxxxxxxx> wrote:
Ananiev, Leonid I writes:
> >From Leonid Ananiev

Hello,

>
> Moving dirty pages balancing from user to kernel thread pdfludh entirely
> reduces extra long write(2) latencies, increases performance.
>

[...]

> The benchmarks IOzone and Sysbench for file size 50% and 120% of
> RAM size on Pentium4, Xeon, Itanium have reported write and mix
> throughput increasing about 25%. The described Iozone > 0.1 sec write(2)

Results are impressive.

Wouldn't this interfere with current->backing_dev_info logic? This field
is set by __generic_file_aio_write_nolock() and checked by
may_write_to_queue() to force heavy writes to do more pageout. Maybe
pdflush threads should set this field too?

> latencies are deleted. The condition writeback_in_progress() is tested
> earlier now. As a result extra pdflush works are not created and number
> of context switches increasing is inside variation limites.

Nikita.

Maybe we should keep the sync-write logic if there is only one online
cpu, and thus avoiding extra context switches when they are not
profitable?

--
Greetz, Antonio Vargas aka winden of network
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/