On Wed, 2 Apr 2003, Abramo Bagnara wrote:
Jaroslav Kysela ha scritto:
I feel we are still thinking in a different way. The separating of volatile data is only access and memory optimization. The code in the control interface uses still linear lookups. Note that there is no restriction to use this "multi" element for matrix only. Then address in
I realized that.
matrix is always mapped to linear one. If you want a gap inside matrix, then set the INACTIVE flag to the access field (volatile data). It's quite
It's not inactive, it does not exists.
complicated to describe such incomplete matrixes in a generic way. Note
? Why complicated?
What about snd_ctl_add_index(ctl, index) (then you can use data tables, loops, wrappers, etc.)
It breaks the linearity and makes lookups much slower.
This is why I combined that with hash table proposal i.e. contemporarily to clean, proper support for generic, maybe sparse, N-dimensional matrix, we would transform id lookup from O(n) to O(1).
that the whole matrix is still represented as one multi element inside the kernel space (except that volatile data are separate for each value inside matrix).
This is true only for non sparse matrix.
Ortogonally to that, IMO the increasing numbers of controls in modern professional hardware justify the choice of hash table access to controls (try to imagine a 26 channel hardware level meter that need to be polled 50 times per second).
I don't mind if I have only one lookup for this set of controls as present in the current code. Actually, the most of cards have around tenths of controls (including HDSP driver after ported to use multi controls) so adding a hash lookup is not a big win in my eyes. Yes, we can do it in future, when we will have hundreds or thousands controls per card.
I agree with you it's only an implementation detail now, but I sent my comments because my feeling is that time for that is already come.
-- Abramo Bagnara mailto:[EMAIL PROTECTED]
Opera Unica Phone: +39.546.656023 Via Emilia Interna, 140 48014 Castel Bolognese (RA) - Italy
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