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From: Chris Metcalf <cmetcalf@mellanox.com>
To: Arnd Bergmann <arnd@arndb.de>, Martin Jambor <mjambor@suse.cz>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	<linux-scsi@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	Denys Vlasenko <dvlasenk@redhat.com>, Thomas Graf <tgraf@suug.ch>,
	Peter Zijlstra <peterz@infradead.org>,
	David Rientjes <rientjes@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Himanshu Madhani <himanshu.madhani@qlogic.com>,
	<qla2xxx-upstream@qlogic.com>, Jan Hubicka <hubicka@ucw.cz>
Subject: Re: [PATCH] scsi: fc: force inlining of wwn conversion functions
Date: Thu, 28 Apr 2016 10:58:43 -0400	[thread overview]
Message-ID: <fb8e623c-9a4f-655e-0670-2f8fa82021a7@mellanox.com> (raw)
In-Reply-To: <4940273.pi2bWg8tAl@wuerfel>

(Resending as text/plain)

On 4/27/2016 5:34 PM, Arnd Bergmann wrote:
> This won't help on TILE, which is the one architecture that sets
> ARCH_SUPPORTS_OPTIMIZED_INLINING but does not set ARCH_USE_BUILTIN_BSWAP.
> Chris Metcalf should be able to figure out whether we can just
> set ARCH_USE_BUILTIN_BSWAP for tile as well.

We certainly could enable ARCH_USE_BUILTIN_BSWAP.  The only problem is
that we never added explicit support for bswap16() in gcc, which is
efficiently done on tilegx via the "revbytes" instruction and a 48-bit
right-shift.  So gcc instead does a generic thing with four
instructions in three bundles, so really not as good as our asm/swab.h.

I'm not sure how to weigh the implications of converting to
builtin_bswap16 (and possibly upstreaming a better implementation to
gcc), vs. disabling ARCH_SUPPORTS_OPTIMIZED_INLINING (which no one
else but x86 uses anyway), vs. just ignoring the compiler bug and
hoping it's not an issue in practice :-)
-- 
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com

  reply	other threads:[~2016-04-28 14:58 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-04 19:45 [PATCH] asm-generic: force inlining of some atomic_long operations Denys Vlasenko
2016-02-04 19:45 ` [PATCH] force inlining of some byteswap operations Denys Vlasenko
2016-02-05  7:28   ` Ingo Molnar
2016-04-13  3:36   ` This patch triggers a bad gcc bug (was Re: [PATCH] force inlining of some byteswap operations) Josh Poimboeuf
2016-04-13 12:12     ` Denys Vlasenko
2016-04-13 12:36       ` Josh Poimboeuf
2016-04-13 15:15         ` Josh Poimboeuf
2016-04-13 16:55           ` James Bottomley
2016-04-13 17:10             ` Josh Poimboeuf
2016-04-14 15:29               ` Denys Vlasenko
2016-04-14 15:57                 ` Josh Poimboeuf
2016-04-14 17:09                   ` Denys Vlasenko
2016-04-15  5:45                     ` Ingo Molnar
2016-04-15 13:47                       ` Josh Poimboeuf
2016-04-15 22:20                         ` Josh Poimboeuf
2016-04-16  9:03                           ` Ingo Molnar
2016-04-18 13:39                             ` Josh Poimboeuf
2016-04-18 14:07                               ` Arnd Bergmann
2016-04-18 14:12                                 ` Josh Poimboeuf
2016-04-18 14:21                                   ` Arnd Bergmann
2016-04-19  8:52                               ` Ingo Molnar
2016-04-19 13:56                                 ` [PATCH] scsi: fc: force inlining of wwn conversion functions Josh Poimboeuf
2016-04-22 23:17                                   ` Quinn Tran
2016-04-25 16:07                                   ` Josh Poimboeuf
2016-04-26  2:40                                     ` Martin K. Petersen
2016-04-26  3:37                                       ` James Bottomley
2016-04-26  7:22                                         ` Arnd Bergmann
2016-04-26  8:35                                           ` Christoph Hellwig
2016-04-26 10:05                                             ` Arnd Bergmann
2016-04-26 13:06                                           ` Martin K. Petersen
2016-04-26 15:58                                             ` Arnd Bergmann
2016-04-26 22:36                                               ` James Bottomley
2016-04-27  0:44                                                 ` Martin K. Petersen
2016-04-27 11:05                                               ` Martin Jambor
2016-04-27 21:34                                                 ` Arnd Bergmann
2016-04-28 14:58                                                   ` Chris Metcalf [this message]
2016-04-28 15:23                                                     ` Arnd Bergmann
2016-04-28 15:48                                                       ` Chris Metcalf
2016-04-27 22:00                                                 ` [PATCH, RFT] byteswap: try to avoid __builtin_constant_p gcc bug Arnd Bergmann
2016-04-27 22:11                                                   ` Josh Poimboeuf
2016-04-28 16:27                                                     ` Quinn Tran
2016-04-16  7:42                       ` This patch triggers a bad gcc bug (was Re: [PATCH] force inlining of some byteswap operations) Arnd Bergmann
2016-04-18 13:22                         ` Josh Poimboeuf
2016-02-04 19:45 ` [PATCH] force inlining of unaligned byteswap operations Denys Vlasenko
2016-02-05  7:28   ` Ingo Molnar

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