linux-kernel - Re: [PATCH 4/9] mm: vmalloc: Add a per-CPU-zone infrastructure

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Message-ID: <ZGzTZWq/hAYCE3DA@pc636>
Date:   Tue, 23 May 2023 16:53:25 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     "Uladzislau Rezki (Sony)" <urezki@...il.com>, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>, Baoquan He <bhe@...hat.com>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Dave Chinner <david@...morbit.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>
Subject: Re: [PATCH 4/9] mm: vmalloc: Add a per-CPU-zone infrastructure

On Mon, May 22, 2023 at 11:08:38PM -0700, Christoph Hellwig wrote:
> On Mon, May 22, 2023 at 01:08:44PM +0200, Uladzislau Rezki (Sony) wrote:
> > +#define fbl(z, i, m) z->fbl[i].m
> > +#define fbl_root(z, i) fbl(z, i, root)
> > +#define fbl_head(z, i) fbl(z, i, head)
> > +
> > +#define fbl_lock(z, i) spin_lock(&fbl(z, i, lock))
> > +#define fbl_unlock(z, i) spin_unlock(&fbl(z, i, lock))
> 
> Even if it is just temporary, I don't think adding these wrappers
> make much sense.
> 
If open-coded, it looks like:

spin_lock(&z->fbl[BUSY].lock);
fbl_lock(z, BUSY);

the reason of adding such helpers is to make the name shorter.

> > +struct cpu_vmap_zone {
> > +	/*
> > +	 * FREE, BUSY, LAZY bookkeeping data of this CPU zone.
> > +	 */
> > +	struct {
> > +		struct rb_root root;
> > +		struct list_head head;
> > +		spinlock_t lock;
> > +	} fbl[NFBL];
> 
> Maybe replace NFBL with something longer and more descriptive?
> 
> But also in general it feels like this should be folded into a patch
> doing real work.  As-is it doesn't look very useful.
>
I split it for better understanding for review. But i can fold it.

--
Uladzislau Rezki