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SubjectRe: [PATCHv4 2/9] zram: Add recompression algorithm sysfs knob
On (22/11/04 10:43), Minchan Kim wrote:
> > > Configure 2 alternative algos, with priority 1 and 2
> > >
> > > echo "name=lz4 priority=1" > recomp_algo
> > > echo "name=lz5 priority=2" > recomp_algo
> > >
> > > Recompress pages using algo 1 and algo 2
> > >
> > > echo "type=huge threshold=3000 algo_idx=1" > recompress
> > > echo "type=idle threshold=2000 algo_idx=2" > recompress
> > >
> > > Maybe we can even pass algo name instead of idx.
> >
> > Or pass priority= so that interface that uses algorithms has the
> > same keyword that the interface that configures those algorithms.
>
> Hmm, why do we need algo_idx here if we already set up every
> fields at algorithm setup time?
>
> My understaind(assuming default(i.e., primary) algo is lzo) is
>
> echo "name=lz4 priority=1" > recomp_algo
> echo "name=lz5 priority=2" > recomp_algo
>
> echo "type=huge threshold=3000" > recompress
>
> It will try compress every objects which greater than 3000B with lz4 first
> and then lz5 if it's stillgreater or equal than 3000(or same size class).

One can be SW one can be HW. So I thought about having flexibility here.
Instead of doing

for (idx = 1; idx < MAX_IDX; idx++) {
len = zcomp_compress(zram->comps[idx]);
if (len <= threshold)
break;
}

We would just directly use the suggested algo.

But we probably don't need that param at all and can use
the loop instead?

[..]
> echo "name=lz4 priority=1" > recomp_algo
> echo "name=lz5 priority=2" > recomp_algo
>
> # or I realized to change lz5 to lz7 so
> echo "name=lz6 priority=2" > recomp_algo

So the latter should delete lz5 at idx 2 and put lz6 there?
I can add that.

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