Changes in block layer for IOScheduler Insertion selection

[mani]

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> wrote:

> On Fri, May 27, 2011 at 8:29 AM, mani <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
> >
> >
> > _______________________________________________
> > Kernelnewbies mailing list
> > Kernelnewbies at kernelnewbies.org
> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >
> >
>
>
>
> --
> Eduardo Silva
> http://edsiper.linuxchile.cl
> http://www.monkey-project.com
>
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