From: Jeff King <peff@peff.net>
To: "René Scharfe" <l.s.r@web.de>
Cc: Git List <git@vger.kernel.org>, Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 4/3] midx: inline nth_midxed_pack_entry()
Date: Sat, 11 Sep 2021 17:20:01 -0400 [thread overview]
Message-ID: <YT0dgTgLVrtS9md6@coredump.intra.peff.net> (raw)
In-Reply-To: <120ffa79-d3cb-2e81-1da6-358e7407ec69@web.de>
On Sat, Sep 11, 2021 at 10:31:34PM +0200, René Scharfe wrote:
> Am 11.09.21 um 19:07 schrieb Jeff King:
> > On Sat, Sep 11, 2021 at 06:08:42PM +0200, René Scharfe wrote:
> >
> >> @@ -304,8 +307,7 @@ static int nth_midxed_pack_entry(struct repository *r,
> >> if (!is_pack_valid(p))
> >> return 0;
> >>
> >> - nth_midxed_object_oid(&oid, m, pos);
> >> - if (oidset_contains(&p->bad_objects, &oid))
> >> + if (oidset_contains(&p->bad_objects, oid))
> >> return 0;
> >
> > So we get to avoid the nth_midxed_object_oid() copy entirely. Very nice.
> >
> > Compared to the code before your series, we still have an extra function
> > call to oidset_contains(), which will (in the common case) notice we
> > have no entries and immediately return. But I think that's getting into
> > pointless micro-optimization.
>
> Right. I measure a 0.5% slowdown for git multi-pack-index verify. An
> inline oidset_size call avoids it. That's easy enough to add, so let's
> have it!
I don't mind that, but I wonder if we can have our cake and eat it, too.
oidset_contains() is short, too, and could be inlined. Or if we're
worried about the size of the embedded kh_get_oid_set() getting inlined,
we could do something like:
static inline int oidset_contains(const struct oidset *set, const
struct object_id *oid)
{
if (!oidset_size(set))
return 0;
return oidset_contains_func(set, oid);
}
That saves callers from having to deal with it, at the expense of a
slightly complicated oidset implementation.
I guess it's an extra integer comparison for callers that _do_ expect to
have a non-empty set. So maybe it is better left to the caller to
decide whether to optimize in this way.
(A totally inline oidset_contains() avoids the extra check, but possibly
at the cost of larger code size).
-Peff
next prev parent reply other threads:[~2021-09-11 21:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-11 7:50 [PATCH 0/3] packfile: use oidset for bad objects René Scharfe
2021-09-11 7:59 ` [PATCH 1/3] packfile: convert mark_bad_packed_object() to object_id René Scharfe
2021-09-11 8:00 ` [PATCH 2/3] packfile: convert has_packed_and_bad() " René Scharfe
2021-09-11 8:01 ` [PATCH 3/3] packfile: use oidset for bad objects René Scharfe
2021-09-11 14:26 ` Jeff King
2021-09-11 16:08 ` René Scharfe
2021-09-11 17:03 ` Jeff King
2021-09-11 17:16 ` René Scharfe
2021-09-11 14:27 ` [PATCH 0/3] " Jeff King
2021-09-11 16:08 ` [PATCH 4/3] midx: inline nth_midxed_pack_entry() René Scharfe
2021-09-11 17:03 ` René Scharfe
2021-09-11 17:07 ` Jeff King
2021-09-11 20:31 ` René Scharfe
2021-09-11 21:20 ` Jeff King [this message]
2021-09-11 23:39 ` René Scharfe
2021-09-11 20:31 ` [PATCH v2 0/5] packfile: use oidset for bad objects René Scharfe
2021-09-11 20:36 ` [PATCH 1/5] oidset: make oidset_size() an inline function René Scharfe
2021-09-11 20:39 ` [PATCH 2/5] midx: inline nth_midxed_pack_entry() René Scharfe
2021-09-11 20:40 ` [PATCH 3/5] packfile: convert mark_bad_packed_object() to object_id René Scharfe
2021-09-11 20:42 ` [PATCH v2 4/5] packfile: convert has_packed_and_bad() " René Scharfe
2021-09-11 20:43 ` [PATCH v2 5/5] packfile: use oidset for bad objects René Scharfe
2021-09-11 20:45 ` [PATCH v2 0/5] " René Scharfe
2021-09-11 21:22 ` Jeff King
2021-09-11 23:59 ` Derrick Stolee
2021-09-12 1:51 ` Taylor Blau
2021-09-12 2:29 ` Taylor Blau
2021-09-12 3:51 ` Derrick Stolee
2021-09-12 4:01 ` Taylor Blau
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