Changes in block layer for IOScheduler Insertion selection

[Matthias Brugger]

On 06/02/2011 05:41 AM, mani wrote:
> Dear All,
>
> Any suggestions on the below point ?

have you tried different benchmarks?
This can give you an idea of the impact. It seems that up to now, you've 
only executed sequential read and write access by one process.

Personally I use the fio benchmark. For flash file systems, David Wagner 
from Free Electrons developed a benchmarksuite. Maybe it would be worse 
having a look on it.

Best regards,
Matthias Brugger

>
> Thanks in advance..
>
> On Mon, May 30, 2011 at 10:53 AM, mani <manishrma at gmail.com 
> <mailto:manishrma at gmail.com>> wrote:
>
>     Dear Eduardo,
>
>        I am using squashfs filesystem. So i am more concern with the
>     read speed.
>         whereas below are the details
>                                                          read speed  
>     write speed
>         ELEVATOR_INSERT_SORT       8 MBps            5MBps
>         ELEVATOR_INSERT_BACK      10 MBps           7.2MBps
>
>        used the following command for measurement for both the cases.
>        reading
>        hdparm -t /dev/mtdblock3
>
>        writing
>        dd if=/dev/zero of=/dev/mtd3 bs=4096 count=100k
>
>        As of now everything is working fine with those changes
>        but i am worried if these changes would have any adverse effect
>     anywhere ?
>
>        Thanks.
>
>
>     On Fri, May 27, 2011 at 8:37 PM, Eduardo Silva <edsiper at gmail.com
>     <mailto:edsiper at gmail.com>> wrote:
>
>         On Fri, May 27, 2011 at 8:29 AM, mani <manishrma at gmail.com
>         <mailto:manishrma at gmail.com>> wrote:
>         >
>         > Dear All,
>         >
>         > I am working on linux kernel 2.6.32.9 tegra NVIDIA board.
>         >
>         > I am getting ~8MBps speed of the Nand disk if i use hdparm
>         > hdparm -t /dev/mtdblock3
>         >
>         > i made changes in block layer of kernel as below:-
>         >
>         > block/blk-core.c
>         > static inline void add_request(struct request_queue *q,
>         struct request *req)
>         > {
>         >         drive_stat_acct(req, 1);
>         >
>         >         /*
>         >          * elevator indicated where it wants this request to be
>         >          * inserted at elevator_merge time
>         >          */
>         >
>         >         __elv_add_request(q, req, ELEVATOR_INSERT_BACK, 0);
>         >         //__elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
>         > }
>         >
>         >
>
>         What are the results for read and write for both cases ?
>
>
>         > changed ELEVATOR_INSERT_SORT to ELEVATOR_INSERT_BACK
>         > it improves my NAND speed to 10MBps.
>         >
>         > I am using "noop" I/O scheduler.
>         >
>         > Will this change have any adverse effect in kernel ? or any
>         other side
>         > effect as far as i am using only Nand no Hard disk.
>         >
>         >
>         > Thanks
>         > Mani
>         >
>         >
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>         >
>         >
>
>
>
>         --
>         Eduardo Silva
>         http://edsiper.linuxchile.cl
>         http://www.monkey-project.com
>
>
>
>
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