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From: vixie@decwrl.dec.com (Paul Vixie)
Newsgroups: comp.unix.wizards,comp.os.misc
Subject: Re: Reducing system calls overhead
Message-ID: <94@volition.dec.com>
Date: 25 Aug 88 23:56:45 GMT
References: <21606@ccicpg.UUCP>
Organization: DEC Western Research Lab
Lines: 14

In article <21606@ccicpg.UUCP> goshen@ccicpg.UUCP (Shmuel Goshen) writes:
# [...] This quick interface will run 
# in kernel mode, thus enabling access to kernel data structures, but 
# will not include operations like saving the context (setjmp), signal 
# delivery and allowing rescheduling upon return from the call. 
# The net effect is almost as having the system call run in user mode. 

It depends on the CPU and MMU.  If you're changing to supervisor mode,
chances are you're switching memory maps / page tables, which on many
CPU/MMU combos means: kiss your cache goodbye (sorry :-)).
-- 
Paul Vixie
Digital Equipment Corporation	Work:  vixie@dec.com	Play:  paul@vixie.UUCP
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