Re: JFFS3 & performance

Artem B. Bityuckiy
2005-01-07T17:57:13Z

On Fri, 7 Jan 2005 jasmine@linuxgrrls.org wrote:

>
>
> On Fri, 7 Jan 2005, Artem B. Bityuckiy wrote:
>
> >> i) The instruction cache suffers from this penalty and is, in fact, the
> >> major issue here. Most of the wasted cycles will be waiting for an
> >> instruction to arrive from the i-cache.
>
> > I'm sorry, not exactly. Ok, could you please write the code you think is
> > better? Currentlly it is:
>
> I don't know. I guess you'd need to use inline assembler to shove the
> code around. I don't know how to do that in Linux any more, but in the
> OS I'm used to it would look something like this:
>
> /* Trash the CPU data chache */
> trash_cache();
> ts1 = TIMESTAMP();
> asm(ALIGN_32);
> for (j = 0; j < memsizes[i]; j++)
> mem[i][j] = mem[i][j] + 1;
> asm(ALIGN_32);
> for (j = 0; j < memsizes[i]; j++)
> mem[i][j] = mem[i][j] + 1;
> ts2 = TIMESTAMP();
>
I don't know simple way eiter. The only idea is somthing like put these to
32-byte aligned sections... So I'd prefer to leave it as it is... Does
this really affect results much?

--
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.