On Sat, Nov 05, 2022 at 08:41:37AM +0900, Sergey Senozhatsky wrote:
> 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?
I don't understand what param you are saying. I expected
the zram->comps array already has sorted algoritm based on the
priority so the loop will try compression as expected so loop is fine.
Are we on same page?
>
> [..]
> > 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.
Yub.
