From: Alexey Tourbin <at@altlinux.ru> To: ALT Devel discussion list <devel@lists.altlinux.org> Subject: Re: [devel] [PATCH 0/3] optimize rpmsetcmp() Date: Sun, 5 Dec 2010 03:21:15 +0300 Message-ID: <20101205002114.GC25886@altlinux.org> (raw) In-Reply-To: <20101205000316.GA5836@altlinux.org> On Sun, Dec 05, 2010 at 03:03:16AM +0300, Dmitry V. Levin wrote: > > > apt-rpm indeed calls rpmRangesOverlap() too many times, it's common > > > knowledge. Unfortunately, stating this fact isn't sufficient to make > > > apt-rpm work faster. > > > > So what do you think? There's a possibility to change bitv[] to bitmap, > > per Kirill's proposal. That mighit yield about, say 30% user time cutdown. > > 30% is a bit optimistic, according to my measurements. > > > However, note that apt is not only eager for user time. System time is > > being spent with splendor as well. > > System time takes only about 15% of elapsed time, according to my > measurements. Under VirtualBox, which seems to become a common hardware nowadays, system time is somewhat more noticable. > > Personally, I like bitv[], and I don't like something like <sys/select.h> stuff. > > When performance is the issue, there should be a good rationale to choose > the approach that works slower. There are other reasons, such as keeping the code comprehensible (at the expense of some runtime penalties). I think the concept of bitv[] is crucial for understanding the code, and it helps to keep the code clean and self-evident. Replacing bitv[] with bitmap might be a major trade-off for the sake of performance. Or might not.
next prev parent reply other threads:[~2010-12-05 0:21 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2010-11-25 22:04 Kirill A. Shutsemov 2010-11-25 22:04 ` [devel] [PATCH 1/3] set.c: use packed bitmap for bit vector Kirill A. Shutsemov 2010-11-25 22:04 ` [devel] [PATCH 2/3] set.c: optimize putbits() Kirill A. Shutsemov 2010-11-25 22:04 ` [devel] [PATCH 3/3] set.c: optimize decode_golomb() Kirill A. Shutsemov 2010-11-26 8:35 ` [devel] [PATCH 0/3] optimize rpmsetcmp() Kirill A. Shutemov 2010-11-30 0:35 ` Dmitry V. Levin 2010-12-02 21:48 ` Dmitry V. Levin 2010-12-04 13:02 ` Alexey Tourbin 2010-12-04 16:30 ` Dmitry V. Levin 2010-12-04 16:55 ` Alexey Tourbin 2010-12-04 15:06 ` Alexey Tourbin 2010-12-04 16:29 ` Dmitry V. Levin 2010-12-04 16:42 ` Alexey Tourbin 2010-12-04 16:52 ` Dmitry V. Levin 2010-12-04 17:05 ` Alexey Tourbin 2010-12-04 17:52 ` Dmitry V. Levin 2010-12-04 21:28 ` Alexey Tourbin 2010-12-04 23:26 ` Dmitry V. Levin 2010-12-04 23:41 ` Alexey Tourbin 2010-12-05 0:03 ` Dmitry V. Levin 2010-12-05 0:21 ` Alexey Tourbin [this message] 2010-12-05 12:49 ` Michael Shigorin 2010-12-07 17:50 ` Dmitry V. Levin 2010-12-05 1:24 ` Alexey Tourbin 2010-12-05 11:18 ` Dmitry V. Levin 2010-12-05 12:39 ` Alexey Tourbin 2010-12-05 12:39 ` Michael Shigorin 2010-12-05 12:58 ` Alexey Tourbin 2010-12-05 15:27 ` Dmitry V. Levin
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