linux-kernel - Re: [PATCH 0/7] minmax: reduce compilation time

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Message-ID: <87b65cac-a7f6-490b-9cdb-617584d3edac@lucifer.local>
Date: Sat, 27 Jul 2024 17:56:59 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Jens Axboe <axboe@...nel.dk>
Cc: Linus Torvalds <torvalds@...uxfoundation.org>,
        David Laight <David.Laight@...lab.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Christoph Hellwig <hch@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Dan Carpenter <dan.carpenter@...aro.org>,
        Arnd Bergmann <arnd@...nel.org>, "Jason@...c4.com" <Jason@...c4.com>,
        "pedro.falcato@...il.com" <pedro.falcato@...il.com>,
        Mateusz Guzik <mjguzik@...il.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH 0/7] minmax: reduce compilation time

On Sat, Jul 27, 2024 at 10:52:32AM GMT, Jens Axboe wrote:
> On 7/27/24 10:41 AM, Lorenzo Stoakes wrote:
> >>> Patch attached including Jens's change + mine.
> >>
> >> bvec side matches what I have here, fwiw, except I also did
> >> mp_bvec_iter_len(). Didn't see big expansion there, but might as well
> >> keep them consistent.
> >
> > Makes sense, am happy to give R-b tag for this patch if you want to put it
> > forward? Not sure if Linus is minded to just pull something for this now?
>
> Here's what I built (allmodconfig, gcc-14 and clang-20) and did a basic
> boot of. Was just going to shove it into the 6.12 queue once posted, but
> can go either way with this. Or Linus can just grab it and run with it,
> not super particular ;-)

Yeah looks good to me, either way have:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

>
> > If we're whack-a-moleing may as well sort the drivers I found in my
> > allmodconfig too obviously as some hilariously low-hanging fruit there...
>
> Oh I'm not, I got plenty of other things to tend to. Just got sucked
> into the block side as that looked nuts, wanted to make that wasn't
> insane.
>

Fully understandable, and it is the weekend after all :)

As I am clearly a bit bored this w/e, I might take a look at the obvious
bits there myself if Linus hasn't already patched...

Have an allmodconfig build going now.

>
> diff --git a/include/linux/bvec.h b/include/linux/bvec.h
> index f41c7f0ef91e..1cb76a829b83 100644
> --- a/include/linux/bvec.h
> +++ b/include/linux/bvec.h
> @@ -101,9 +101,14 @@ struct bvec_iter_all {
>  #define mp_bvec_iter_page(bvec, iter)				\
>  	(__bvec_iter_bvec((bvec), (iter))->bv_page)
>
> -#define mp_bvec_iter_len(bvec, iter)				\
> -	min((iter).bi_size,					\
> -	    __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
> +static inline unsigned mp_bvec_iter_len(const struct bio_vec *bvec,
> +					struct bvec_iter iter)
> +{
> +	unsigned remains = __bvec_iter_bvec(bvec, iter)->bv_len -
> +				iter.bi_bvec_done;
> +
> +	return remains < iter.bi_size ? remains : iter.bi_size;
> +}
>
>  #define mp_bvec_iter_offset(bvec, iter)				\
>  	(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
> @@ -111,12 +116,15 @@ struct bvec_iter_all {
>  #define mp_bvec_iter_page_idx(bvec, iter)			\
>  	(mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)
>
> -#define mp_bvec_iter_bvec(bvec, iter)				\
> -((struct bio_vec) {						\
> -	.bv_page	= mp_bvec_iter_page((bvec), (iter)),	\
> -	.bv_len		= mp_bvec_iter_len((bvec), (iter)),	\
> -	.bv_offset	= mp_bvec_iter_offset((bvec), (iter)),	\
> -})
> +static inline struct bio_vec mp_bvec_iter_bvec(const struct bio_vec *bv,
> +					       struct bvec_iter iter)
> +{
> +	return (struct bio_vec) {
> +		.bv_page	= mp_bvec_iter_page(bv, iter),
> +		.bv_len		= mp_bvec_iter_len(bv, iter),
> +		.bv_offset	= mp_bvec_iter_offset(bv, iter)
> +	};
> +}
>
>  /* For building single-page bvec in flight */
>   #define bvec_iter_offset(bvec, iter)				\
> @@ -130,12 +138,15 @@ struct bvec_iter_all {
>  	(mp_bvec_iter_page((bvec), (iter)) +			\
>  	 mp_bvec_iter_page_idx((bvec), (iter)))
>
> -#define bvec_iter_bvec(bvec, iter)				\
> -((struct bio_vec) {						\
> -	.bv_page	= bvec_iter_page((bvec), (iter)),	\
> -	.bv_len		= bvec_iter_len((bvec), (iter)),	\
> -	.bv_offset	= bvec_iter_offset((bvec), (iter)),	\
> -})
> +static inline struct bio_vec bvec_iter_bvec(const struct bio_vec *bv,
> +					    struct bvec_iter iter)
> +{
> +	return (struct bio_vec) {
> +		.bv_page	= bvec_iter_page(bv, iter),
> +		.bv_len		= bvec_iter_len(bv, iter),
> +		.bv_offset	= bvec_iter_offset(bv, iter)
> +	};
> +}
>
>  static inline bool bvec_iter_advance(const struct bio_vec *bv,
>  		struct bvec_iter *iter, unsigned bytes)
>
> --
> Jens Axboe
>
>