Messages in this thread | | | Date | Mon, 23 Sep 2019 12:02:59 +0200 | From | Jan Kara <> | Subject | Re: [PATCH] quota: code cleanup for hash bits calculation |
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On Sat 21-09-19 09:56:28, Chengguang Xu wrote: > Code cleanup for hash bits calculation by > calling rounddown_pow_of_two() and ilog2() > > Signed-off-by: Chengguang Xu <cgxu519@zoho.com.cn>
Thanks for the patch! One comment below:
> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c > index 6e826b454082..679dd3b5db70 100644 > --- a/fs/quota/dquot.c > +++ b/fs/quota/dquot.c > @@ -2983,13 +2983,9 @@ static int __init dquot_init(void) > > /* Find power-of-two hlist_heads which can fit into allocation */ > nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head); > - dq_hash_bits = 0; > - do { > - dq_hash_bits++; > - } while (nr_hash >> dq_hash_bits); > - dq_hash_bits--; > + nr_hash = rounddown_pow_of_two(nr_hash); > + dq_hash_bits = ilog2(nr_hash); > > - nr_hash = 1UL << dq_hash_bits;
Why not just: dq_hash_bits = ilog2(nr_hash); nr_hash = 1UL << dq_hash_bits;
That way we need to compute fls() only once...
Honza -- Jan Kara <jack@suse.com> SUSE Labs, CR
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