From: Randolph Chung <randolph@tausq.org>
To: parisc-linux@lists.parisc-linux.org
Subject: [parisc-linux] Improving performance of munmap
Date: Thu, 7 Oct 2004 16:02:32 -0700 [thread overview]
Message-ID: <20041007230232.GF14151@tausq.org> (raw)
Hi all,
On a 2.6 SMP kernel, munmap()ing 16MB currently takes on the order of
0.8-0.9 seconds on a 440MHz machine. on a UP machine it takes about 5ms.
profiling shows that we are spending a lot of time flushing caches:
tausq@ios:~/parisc/linux-2.6$ sort -nr -k3 ~/test/mmap/after |head
48586 cpu_idle 759.1562
37906 machine_restart 592.2812
10951 flush_user_icache_range_asm 304.1944
10946 flush_user_dcache_range_asm 304.0556
129 flush_kernel_icache_page 1.2900
29 _spin_unlock_bh 0.6042
9 fdsync 0.4500
10 _spin_unlock_irq 0.4167
i believe this is related to the way we implement flush_tlb_mm(). on SMP
we currently flush the entire tlb, instead of just invaliding the
process context. this is needed to get the correct behavior if a
multithreaded app is simultaneously running on >1 CPUs. James had
suggested previously that we might be able to do something smarter, such
as sending an ipi to the other CPU to switch the context.
would anybody like to look into this problem, or suggest some ways to
tackle this?
randolph
--
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/
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next reply other threads:[~2004-10-07 23:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-07 23:02 Randolph Chung [this message]
2004-10-08 2:03 ` [parisc-linux] Improving performance of munmap Carlos O'Donell
2004-10-08 4:16 ` Randolph Chung
2004-10-08 16:59 ` Randolph Chung
2004-10-08 17:05 ` Randolph Chung
2004-10-08 17:35 ` Grant Grundler
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