From: Greg Ungerer <gregungerer@westnet.com.au>
To: Matthew Wilcox <willy@infradead.org>
Cc: David Laight <David.Laight@aculab.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH 09/17] m68k: Implement xor_unlock_is_negative_byte
Date: Wed, 4 Oct 2023 22:06:29 +1000 [thread overview]
Message-ID: <22caaecc-c954-d880-672f-45761bf7fac2@westnet.com.au> (raw)
In-Reply-To: <ZRx0lIo5i2EuIsZ/@casper.infradead.org>
On 4/10/23 06:07, Matthew Wilcox wrote:
> On Wed, Oct 04, 2023 at 12:14:10AM +1000, Greg Ungerer wrote:
>> On 3/10/23 06:07, Matthew Wilcox wrote:
>>> 00000918 <folio_unlock>:
>>> 918: 206f 0004 moveal %sp@(4),%a0
>>> 91c: 7001 moveq #1,%d0
>>> 91e: b190 eorl %d0,%a0@
>>> 920: 2010 movel %a0@,%d0
>>> 922: 4a00 tstb %d0
>>> 924: 6a0a bpls 930 <folio_unlock+0x18>
>>> 926: 42a7 clrl %sp@-
>>> 928: 2f08 movel %a0,%sp@-
>>> 92a: 4eba fafa jsr %pc@(426 <folio_wake_bit>)
>>> 92e: 508f addql #8,%sp
>>> 930: 4e75 rts
>
> fwiw, here's what folio_unlock looks like today without any of my
> patches:
>
> 00000746 <folio_unlock>:
> 746: 206f 0004 moveal %sp@(4),%a0
> 74a: 43e8 0003 lea %a0@(3),%a1
> 74e: 0891 0000 bclr #0,%a1@
> 752: 2010 movel %a0@,%d0
> 754: 4a00 tstb %d0
> 756: 6a0a bpls 762 <folio_unlock+0x1c>
> 758: 42a7 clrl %sp@-
> 75a: 2f08 movel %a0,%sp@-
> 75c: 4eba fcc8 jsr %pc@(426 <folio_wake_bit>)
> 760: 508f addql #8,%sp
> 762: 4e75 rts
>
> Same number of instructions, but today's code has slightly longer insns,
> so I'm tempted to take the win?
Yes, I reckon so.
>>> We could use eori instead of eorl, at least according to table 3-9 on
>>> page 3-8:
>>>
>>> EOR Dy,<ea>x L Source ^ Destination → Destination ISA_A
>>> EORI #<data>,Dx L Immediate Data ^ Destination → Destination ISA_A
>
> Oh. I misread. It only does EORI to a data register; it can't do EORI
> to an address.
>
>> 400413e6 <folio_unlock>:
>> 400413e6: 206f 0004 moveal %sp@(4),%a0
>> 400413ea: 2010 movel %a0@,%d0
>> 400413ec: 0a80 0000 0001 eoril #1,%d0
>> 400413f2: 2080 movel %d0,%a0@
>> 400413f4: 2010 movel %a0@,%d0
>> 400413f6: 4a00 tstb %d0
>> 400413f8: 6c0a bges 40041404 <folio_unlock+0x1e>
>> 400413fa: 42a7 clrl %sp@-
>> 400413fc: 2f08 movel %a0,%sp@-
>> 400413fe: 4eba ff30 jsr %pc@(40041330 <folio_wake_bit>)
>> 40041402: 508f addql #8,%sp
>> 40041404: 4e75 rts
>>
>> But that is still worse anyway.
>
> Yup. Looks like the version I posted actually does the best! I'll
> munge that into the patch series and repost. Thanks for your help!
No worries. Sorry I didn't notice it earlier, but glad it is sorted now.
Regards
Greg
next prev parent reply other threads:[~2023-10-04 12:36 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-15 18:36 [PATCH 00/17] Add folio_end_read Matthew Wilcox (Oracle)
2023-09-15 18:36 ` [PATCH 01/17] iomap: Hold state_lock over call to ifs_set_range_uptodate() Matthew Wilcox (Oracle)
2023-09-15 18:36 ` [PATCH 02/17] iomap: Protect read_bytes_pending with the state_lock Matthew Wilcox (Oracle)
2023-09-16 0:11 ` Linus Torvalds
2023-09-16 0:15 ` Linus Torvalds
2023-09-16 15:50 ` Matthew Wilcox
2023-09-15 18:36 ` [PATCH 03/17] mm: Add folio_end_read() Matthew Wilcox (Oracle)
2023-09-15 18:36 ` [PATCH 04/17] ext4: Use folio_end_read() Matthew Wilcox (Oracle)
2023-09-15 18:36 ` [PATCH 05/17] buffer: " Matthew Wilcox (Oracle)
2023-09-15 18:36 ` [PATCH 06/17] iomap: " Matthew Wilcox (Oracle)
2023-09-15 18:36 ` [PATCH 07/17] bitops: Add xor_unlock_is_negative_byte() Matthew Wilcox (Oracle)
2023-09-15 18:36 ` [PATCH 08/17] alpha: Implement xor_unlock_is_negative_byte Matthew Wilcox (Oracle)
2023-09-16 0:27 ` Linus Torvalds
2023-09-16 0:38 ` Matthew Wilcox
2023-09-16 2:01 ` Linus Torvalds
2023-09-16 2:14 ` Linus Torvalds
2023-09-16 15:59 ` Matthew Wilcox
2023-09-15 18:36 ` [PATCH 09/17] m68k: " Matthew Wilcox (Oracle)
2023-09-16 13:11 ` Greg Ungerer
2023-09-16 14:34 ` Matthew Wilcox
2023-09-18 14:37 ` Greg Ungerer
2023-09-20 7:45 ` Greg Ungerer
2023-09-20 16:58 ` Linus Torvalds
2023-09-19 13:23 ` David Laight
2023-09-19 14:26 ` Matthew Wilcox
2023-09-19 14:35 ` David Laight
2023-09-19 15:14 ` Matthew Wilcox
2023-09-19 15:22 ` David Laight
2023-09-19 15:47 ` Matthew Wilcox
2023-09-19 15:57 ` David Laight
2023-09-20 7:15 ` Greg Ungerer
2023-09-20 7:22 ` Greg Ungerer
2023-10-02 20:07 ` Matthew Wilcox
2023-10-03 14:14 ` Greg Ungerer
2023-10-03 20:07 ` Matthew Wilcox
2023-10-04 12:06 ` Greg Ungerer [this message]
2023-09-15 18:37 ` [PATCH 10/17] mips: " Matthew Wilcox (Oracle)
2023-09-15 18:37 ` [PATCH 11/17] powerpc: Implement arch_xor_unlock_is_negative_byte on 32-bit Matthew Wilcox (Oracle)
2023-09-15 18:37 ` [PATCH 12/17] riscv: Implement xor_unlock_is_negative_byte Matthew Wilcox (Oracle)
2023-09-15 18:37 ` [PATCH 13/17] s390: Implement arch_xor_unlock_is_negative_byte Matthew Wilcox (Oracle)
2023-09-15 18:37 ` [PATCH 14/17] mm: Delete checks for xor_unlock_is_negative_byte() Matthew Wilcox (Oracle)
2023-09-15 18:37 ` [PATCH 15/17] mm: Add folio_xor_flags_has_waiters() Matthew Wilcox (Oracle)
2023-09-15 18:37 ` [PATCH 16/17] mm: Make __end_folio_writeback() return void Matthew Wilcox (Oracle)
2023-09-15 18:37 ` [PATCH 17/17] mm: Use folio_xor_flags_has_waiters() in folio_end_writeback() Matthew Wilcox (Oracle)
2023-09-16 0:31 ` [PATCH 00/17] Add folio_end_read Linus Torvalds
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