Am 09.01.2017 um 02:54 schrieb Yan, Zheng:
On 8 Jan 2017, at 00:31, Ilya Dryomov <idryomov@xxxxxxxxx> wrote:
On Thu, Jan 5, 2017 at 4:23 PM, Andreas Gerstmayr
<andreas.gerstmayr@xxxxxxxxxxxx> wrote:
This patch sets the io_pages bdi hint based on the rvsize mount option.
Without this patch large buffered reads (request size > max readahead)
are processed sequentially in chunks of the readahead size (i.e. read
requests are sent out up to the readahead size, then the
do_generic_file_read() function waits until the first page is received).
With this patch read requests are sent out up to the size specified in
the new rvsize mount option at once (default: 64 MB).
Signed-off-by: Andreas Gerstmayr <andreas.gerstmayr@xxxxxxxxxxxx>
---
Thanks for your review.
On second thought, I think I should not reuse the rsize mount option
(maximum read size per OSD request), therefore I created a new mount
option rvsize with a default value of 64 MB (as you suggested).
(Note: This patch depends on kernel version 4.10-rc1)
I'll defer to Zheng's judgement, but a separate mount option for this
seems overkill to me. We should be able to work something out between
the existing rsize and rasize.
I agree with Ilya. I think we can user rsize here.
But then we are using a single config option for two different purposes?
- to specify the maximum size of a single read request to an OSD
- to specify the maximum cumulative size of read requests sent out at
once
In general the latter will be a multiple of the former.
Regards,
Andreas
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