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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Saeed Mahameed <saeedm@mellanox.com>,
	Leon Romanovsky <leon@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Tariq Toukan <tariqt@mellanox.com>,
	Eran Ben Elisha <eranbe@mellanox.com>,
	Boris Pismenny <borisp@mellanox.com>,
	Ilya Lesokhin <ilyal@mellanox.com>,
	Moshe Shemesh <moshe@mellanox.com>,
	Kamal Heib <kamalh@mellanox.com>,
	netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net/mlx5e: fix high stack usage
Date: Fri, 2 Nov 2018 10:08:58 -0600	[thread overview]
Message-ID: <20181102160858.GA17096@ziepe.ca> (raw)
In-Reply-To: <20181102153316.1492515-1-arnd@arndb.de>

On Fri, Nov 02, 2018 at 04:33:03PM +0100, Arnd Bergmann wrote:
> A patch that looks harmless causes the stack usage of the mlx5e_grp_sw_update_stats()
> function to drastically increase with x86 gcc-4.9 and higher (tested up to 8.1):
> 
> drivers/net/ethernet/mellanox/mlx5/core/en_stats.c: In function ‘mlx5e_grp_sw_update_stats’:
> drivers/net/ethernet/mellanox/mlx5/core/en_stats.c:216:1: warning: the frame size of 1276 bytes is larger than 500 bytes [-Wframe-larger-than=]

Why is the stack size so big here? The mlx5e_sw_stats is < 500 bytes
and all the other on-stack stuff looks pretty small?

> By splitting out the loop body into a non-inlined function, the stack size goes
> back down to under 500 bytes.

Does this actually reduce the stack consumed or does this just suppress
the warning?

Jason

  reply	other threads:[~2018-11-02 16:08 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-02 15:33 [PATCH] net/mlx5e: fix high stack usage Arnd Bergmann
2018-11-02 16:08 ` Jason Gunthorpe [this message]
2018-11-02 16:23   ` Arnd Bergmann
2018-11-02 17:00     ` Jason Gunthorpe
2018-11-02 21:05 ` Saeed Mahameed
2018-11-02 21:39   ` Eric Dumazet
2018-11-02 22:07     ` Saeed Mahameed
2018-11-02 22:15       ` Arnd Bergmann
2018-11-03  0:52         ` Saeed Mahameed
2018-11-02 22:15       ` Jason Gunthorpe
2018-11-03  0:37         ` Saeed Mahameed
2018-11-05 11:24 ` David Laight

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