By: none (none.delete@this.none.com), February 23, 2021 8:37 am
Room: Moderated Discussions
Anon (no.delete@this.spam.com) on February 23, 2021 6:21 am wrote:
> anon2 (anon.delete@this.anon.com) on February 23, 2021 4:20 am wrote:
> > Apparently not easy for Intel though because they've been at it for years, every generation
> > telling us that finally rep mov doesn't suck, and every generation we find rep mov sucks.
>
> Which only proves Intel don't put much effort in it, and memcpy isn't the
> only case, gather sucked for generations until Skylake, Intel really loves
> having a lot of poorly implemented instructions, which proves nothing.
>
> > Which terrible ISAs / implementation are you talking about here?
>
> About any implementation that have several ifs to choose the
> most apropriate case and takes up to a few kB of the I$.
>
> > If they suck so bad at memcpy
> > then they must be even more inefficient to implement all other kinds of data movement that an
> > application will do, which (being ~everything except memcpy) is even more common than memcpy.
>
> No, memcpy is the most common memory operation, the other kind of data movement
> is more complex, a situation where there is advantages in doing by software.
So Intel doesn't care about the most common memory operation? Are they that incompetent? Or
is it just that it is quite difficult to make it fast?
> anon2 (anon.delete@this.anon.com) on February 23, 2021 4:20 am wrote:
> > Apparently not easy for Intel though because they've been at it for years, every generation
> > telling us that finally rep mov doesn't suck, and every generation we find rep mov sucks.
>
> Which only proves Intel don't put much effort in it, and memcpy isn't the
> only case, gather sucked for generations until Skylake, Intel really loves
> having a lot of poorly implemented instructions, which proves nothing.
>
> > Which terrible ISAs / implementation are you talking about here?
>
> About any implementation that have several ifs to choose the
> most apropriate case and takes up to a few kB of the I$.
>
> > If they suck so bad at memcpy
> > then they must be even more inefficient to implement all other kinds of data movement that an
> > application will do, which (being ~everything except memcpy) is even more common than memcpy.
>
> No, memcpy is the most common memory operation, the other kind of data movement
> is more complex, a situation where there is advantages in doing by software.
So Intel doesn't care about the most common memory operation? Are they that incompetent? Or
is it just that it is quite difficult to make it fast?