From: David Mosberger <davidm@napali.hpl.hp.com>
To: linux-ia64@vger.kernel.org
Subject: Re: shared memory segment size alignment
Date: Fri, 16 Jan 2004 19:18:57 +0000 [thread overview]
Message-ID: <16392.14625.163460.993083@napali.hpl.hp.com> (raw)
In-Reply-To: <20040116183111.96883.qmail@web60002.mail.yahoo.com>
>>>>> On Fri, 16 Jan 2004 10:31:11 -0800 (PST), umut aymakoglu <umutaymak@yahoo.com> said:
umut> Hi - In some kernel versions the SHMLBA is defined as
umut> 1MB(1024*1024) and in some as 16K. What would be the
umut> difference between aligning the shared memory segment size on
umut> 1MB versus 16K before calling shmget()? Would there be any
umut> performance gain/lose? We are aligning the segment address on
umut> 1MB.
The ia64 architecture allows CPUs to have a performance penalty when
there is virtual aliasing below a 1MB boundary. So if you don't align
to 1MB, it _could_ run slower. No existing processor models do that,
but future models might.
--david
prev parent reply other threads:[~2004-01-16 19:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-16 18:31 shared memory segment size alignment umut aymakoglu
2004-01-16 19:18 ` David Mosberger [this message]
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