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Date:   Fri, 1 Feb 2019 14:03:46 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     "Tobin C. Harding" <tobin@kernel.org>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/slab: Increase width of first /proc/slabinfo column
Message-Id: <20190201140346.fdcd6c4b663fbe3b5d93820d@linux-foundation.org>
In-Reply-To: <20190201024310.GC26359@bombadil.infradead.org>
References: <20190201004242.7659-1-tobin@kernel.org>
        <20190201024310.GC26359@bombadil.infradead.org>
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On Thu, 31 Jan 2019 18:43:10 -0800 Matthew Wilcox <willy@infradead.org> wrote:

> On Fri, Feb 01, 2019 at 11:42:42AM +1100, Tobin C. Harding wrote:
> > Currently when displaying /proc/slabinfo if any cache names are too long
> > then the output columns are not aligned.  We could do something fancy to
> > get the maximum length of any cache name in the system or we could just
> > increase the hardcoded width.  Currently it is 17 characters.  Monitors
> > are wide these days so lets just increase it to 30 characters.
> 
> I had a proposal some time ago to turn the slab name from being kmalloced
> to being an inline 16 bytes (with some fun hacks for cgroups).  I think
> that's a better approach than permitting such long names.  For example,
> ext4_allocation_context could be shortened to ext4_alloc_ctx without
> losing any expressivity.
> 

There are some back-compatibility concerns here.  And truncating long
names might result in duplicates.