From: George Spelvin <lkml@sdf.org>
To: adrian.hunter@intel.com, ard.biesheuvel@linaro.org,
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Subject: Re: [PATCH 0/5] simple sort swap function usage improvements
Date: Sat, 30 Mar 2019 17:16:02 GMT [thread overview]
Message-ID: <201903301716.x2UHG23t020732@sdf.org> (raw)
In-Reply-To: <18626931553963861@sas1-b3ec53dbc12b.qloud-c.yandex.net>
Great work; that is indeed a logical follow-on.
Reviewed by: George Spelvin <lkml@sdf.org>
I you feel even more ambitious, you could try impementing Rasmus
Villemoes' idea of having generic *compare* functions. (It's on
my to-do list, but I haven't made meaningful progress yet, and I'm
happy to pawn it off.)
A significant fraction of the time, the sort key is a 4- or 8-byte
integer field in a structure at a small offset from the base or
list_head.
A function pointer < 4096 could be interpreted as encoding:
- Key size (1 bit)
- Key signedness (1 bit)
- Sort direction (1 bit)
- Offset (9 bits; +/-256 words = +/-1024 bytes, or 0..511 words from start)
With the correct level of preprocessor hackery,
SIMPLE_CMP_ASCENDING(struct type, key_field)
SIMPLE_LIST_CMP_ASCENDING(struct type, list_field, key_field)
SIMPLE_CMP_DESCENDING(struct type, key_field)
SIMPLE_LIST_CMP_DESCENDING(struct type, list_field, key_field)
could encode all that and cause a compile-time error if the key
is the wrong type or the offset is out of range.
next prev parent reply other threads:[~2019-03-30 17:19 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-30 16:37 [PATCH 0/5] simple sort swap function usage improvements Andrey Abramov
2019-03-30 16:40 ` [PATCH 1/5] arch/arc: unwind.c: replace swap function with built-in one Andrey Abramov
2019-03-30 16:41 ` [PATCH 2/5] powerpc: module_[32|64].c: " Andrey Abramov
[not found] ` <87zhpaox14.fsf@concordia.ellerman.id.au>
2019-04-02 19:11 ` Andrey Abramov
2019-03-30 16:42 ` [PATCH 3/5] ocfs2: dir,refcounttree,xattr: replace swap functions " Andrey Abramov
2019-03-30 16:43 ` [PATCH 4/5] ubifs: find.c: replace swap function " Andrey Abramov
2019-03-30 16:43 ` [PATCH 5/5] Lib: sort.h: replace int size with size_t size in the swap function Andrey Abramov
[not found] ` <20190330183826.GB21828@kroah.com>
2019-03-30 20:15 ` George Spelvin
2019-03-30 20:24 ` Greg KH
2019-03-30 21:49 ` George Spelvin
2019-03-31 7:00 ` Andrey Abramov
2019-03-31 10:54 ` gregkh
2019-04-01 14:47 ` David Laight
2019-04-01 18:01 ` Vineet Gupta
2019-04-01 18:14 ` Andrey Abramov
2019-04-01 18:22 ` Vineet Gupta
2019-03-30 17:16 ` George Spelvin [this message]
2019-04-01 21:08 ` [PATCH 0/5] simple sort swap function usage improvements Rasmus Villemoes
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