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From: Timothy Miller <miller@techsource.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ulrich Drepper <drepper@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: hammer: MAP_32BIT
Date: Fri, 09 May 2003 18:46:47 -0400	[thread overview]
Message-ID: <3EBC2FD7.2080007@techsource.com> (raw)
In-Reply-To: 3EBC2996.2040908@zytor.com



H. Peter Anvin wrote:
> Timothy Miller wrote:
> 
>>If your program is capable of handling an address with more than 32
>>bits, what point is there giving a hint?  Either your program can handle
>>64-bit pointers or it cannot.  Any program flexible enough to handle
>>either size dynamically would expend enough overhead checking that it
>>would be worse than if it just made a hard choice.
>>
> 
> 
> The purpose is that there is a slight task-switching speed advantage if
> the address is in the bottom 4 GB.  Since this affects every process,
> and most processes use very little TLS, this is worthwhile.
> 
> This is fundamentally due to a K8 design flaw.

Is there an explicit check somewhere for this?  Are the page tables laid 
out differently?


  reply	other threads:[~2003-05-09 22:29 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-05-09  7:35 hammer: MAP_32BIT Ulrich Drepper
2003-05-09  9:20 ` Andi Kleen
2003-05-09 11:28   ` mikpe
2003-05-09 11:38     ` Andi Kleen
2003-05-09 11:52       ` mikpe
2003-05-09 12:16         ` Andi Kleen
2003-05-09 18:11       ` H. Peter Anvin
2003-05-09 19:24         ` Ulrich Drepper
2003-05-09 20:55           ` H. Peter Anvin
2003-05-09 21:45             ` Ulrich Drepper
2003-05-09 22:07               ` H. Peter Anvin
2003-05-09 22:20                 ` Ulrich Drepper
2003-05-09 22:21                   ` H. Peter Anvin
2003-05-09 22:20               ` Timothy Miller
2003-05-09 22:20                 ` H. Peter Anvin
2003-05-09 22:46                   ` Timothy Miller [this message]
2003-05-09 23:24                     ` H. Peter Anvin
2003-05-13 14:25                       ` Timothy Miller
2003-05-09 22:22                 ` Ulrich Drepper
2003-05-09 22:53                   ` Timothy Miller
2003-05-09 23:24                     ` Ulrich Drepper
2003-05-10  0:00                       ` Edgar Toernig
2003-05-10  0:58                         ` Ulrich Drepper
2003-05-10  2:51                           ` Edgar Toernig
2003-05-09 17:36   ` H. Peter Anvin
2003-05-09 17:39   ` Ulrich Drepper
2003-05-10  1:48     ` Andi Kleen
2003-05-10 20:10       ` David Woodhouse
2003-05-13 18:54         ` H. Peter Anvin

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