Re: [PATCH 3/3] percpu: allow select gfp to be passed to underlying allocators

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From: Dennis Zhou <dennisszhou@gmail.com>
To: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] percpu: allow select gfp to be passed to underlying allocators
Date: Thu, 15 Feb 2018 17:17:14 -0600	[thread overview]
Message-ID: <20180215231714.GB79973@localhost> (raw)
In-Reply-To: <20180215214148.GV695913@devbig577.frc2.facebook.com>

Hi,

On Thu, Feb 15, 2018 at 01:41:48PM -0800, Tejun Heo wrote:
> On Thu, Feb 15, 2018 at 10:08:16AM -0600, Dennis Zhou wrote:
> > +/* the whitelisted flags that can be passed to the backing allocators */
> > +#define gfp_percpu_mask(gfp) (((gfp) & (__GFP_NORETRY | __GFP_NOWARN)) | \
> > +			      GFP_KERNEL)
> 
> Isn't there just one place where gfp comes in from outside?  If so,
> this looks like a bit of overkill.  Can't we just filter there?
> 

I agree, but it's also nice having a single place where flags can be
added or removed. The primary motivator was for the "| GFP_KERNEL", but
as suggested in the other patch this is getting removed. I guess I still
lean towards having it as it's explicit and helps gate both the balance
path and the user allocation path.

Thanks,
Dennis

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WARNING: multiple messages have this Message-ID (diff)

From: Dennis Zhou <dennisszhou@gmail.com>
To: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] percpu: allow select gfp to be passed to underlying allocators
Date: Thu, 15 Feb 2018 17:17:14 -0600	[thread overview]
Message-ID: <20180215231714.GB79973@localhost> (raw)
In-Reply-To: <20180215214148.GV695913@devbig577.frc2.facebook.com>

Hi,

On Thu, Feb 15, 2018 at 01:41:48PM -0800, Tejun Heo wrote:
> On Thu, Feb 15, 2018 at 10:08:16AM -0600, Dennis Zhou wrote:
> > +/* the whitelisted flags that can be passed to the backing allocators */
> > +#define gfp_percpu_mask(gfp) (((gfp) & (__GFP_NORETRY | __GFP_NOWARN)) | \
> > +			      GFP_KERNEL)
> 
> Isn't there just one place where gfp comes in from outside?  If so,
> this looks like a bit of overkill.  Can't we just filter there?
> 

I agree, but it's also nice having a single place where flags can be
added or removed. The primary motivator was for the "| GFP_KERNEL", but
as suggested in the other patch this is getting removed. I guess I still
lean towards having it as it's explicit and helps gate both the balance
path and the user allocation path.

Thanks,
Dennis

next prev parent reply	other threads:[~2018-02-15 23:17 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-15 16:08 [PATCH 0/3] percpu: introduce no retry semantics and gfp passthrough Dennis Zhou
2018-02-15 16:08 ` Dennis Zhou
2018-02-15 16:08 ` [PATCH 1/3] percpu: match chunk allocator declarations with definitions Dennis Zhou
2018-02-15 16:08   ` Dennis Zhou
2018-02-15 16:39   ` Christopher Lameter
2018-02-15 16:39     ` Christopher Lameter
2018-02-15 16:08 ` [PATCH 2/3] percpu: add __GFP_NORETRY semantics to the percpu balancing path Dennis Zhou
2018-02-15 16:08   ` Dennis Zhou
2018-02-15 21:39   ` Tejun Heo
2018-02-15 21:39     ` Tejun Heo
2018-02-15 23:10     ` Dennis Zhou
2018-02-15 23:10       ` Dennis Zhou
2018-02-16 18:07   ` [PATCH v2 " Dennis Zhou
2018-02-16 18:07     ` Dennis Zhou
2018-02-15 16:08 ` [PATCH 3/3] percpu: allow select gfp to be passed to underlying allocators Dennis Zhou
2018-02-15 16:08   ` Dennis Zhou
2018-02-15 21:41   ` Tejun Heo
2018-02-15 21:41     ` Tejun Heo
2018-02-15 23:17     ` Dennis Zhou [this message]
2018-02-15 23:17       ` Dennis Zhou
2018-02-16 18:09   ` [PATCH v2 " Dennis Zhou
2018-02-16 18:09     ` Dennis Zhou
2018-02-18 13:33     ` Tejun Heo
2018-02-18 13:33       ` Tejun Heo

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