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Date:      Sun, 24 Feb 2002 11:49:12 +1100 (EST)
From:      Bruce Evans <bde@zeta.org.au>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        Terry Lambert <tlambert2@mindspring.com>, Alfred Perlstein <alfred@FreeBSD.ORG>, Bosko Milekic <bmilekic@unixdaemons.com>, Seigo Tanimura <tanimura@r.dl.itc.u-tokyo.ac.jp>, <current@FreeBSD.ORG>, John Baldwin <jhb@FreeBSD.ORG>
Subject:   Re: malloc_bucket() idea (was Re: How to fix malloc.)
Message-ID:  <20020224111043.W30980-100000@gamplex.bde.org>
In-Reply-To: <200202240003.g1O036164477@apollo.backplane.com>

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On Sat, 23 Feb 2002, Matthew Dillon wrote:

> :My version of it does less than this.  I only use it to help implement
> :spinlocks.
>
>     You put together infrastructure to deal with pending pci interrupts?
>     If so, then why not commit it (or at least commit a version #ifdef'd
>     for the i386 architecture).

It's too messy and unfinished (doesn't work right for SMP or irqs >= 16),
and dificult to untangle from my other patches.  I posted these partial
ones to attempt to inhibit() recomplication of the current critical*
functions in directions that I don't want to go :-).

> :Index: kern_switch.c
> :===================================================================
> :RCS file: /home/ncvs/src/sys/kern/kern_switch.c,v
> :retrieving revision 1.20
> :diff -u -2 -r1.20 kern_switch.c
> :--- kern_switch.c	11 Feb 2002 20:37:51 -0000	1.20
> :+++ kern_switch.c	13 Feb 2002 05:34:20 -0000
> :@@ -70,14 +70,21 @@
> : }
> :
> :-/* Critical sections that prevent preemption. */
> :+/*-
> :+ * Critical section handling.
> :+ * XXX doesn't belong here.
> :+ *
> :+ * Entering a critical section only blocks non-fast interrupts.
> :+ * critical_enter() is similar to splhigh() in a 2-level spl setup under
> :+ * old versions of FreeBSD.
> :+ *
> :+ * Exiting from all critical sections unblocks non-fast interrupts and runs
> :+ * the handlers of any that were blocked.  critical_exit() is similar to
> :+ * spl(old_level) in a 2-level spl setup under old versions of FreeBSD.
> :+ */
> : void
> : critical_enter(void)
> : {
> :-	struct thread *td;
> :
> :-	td = curthread;
> :-	if (td->td_critnest == 0)
> :-		td->td_savecrit = cpu_critical_enter();
> :-	td->td_critnest++;
> :+	curthread->td_critnest++;
> : }
> :
> :@@ -85,12 +92,7 @@
> : critical_exit(void)
> : {
> :-	struct thread *td;
> :
> :-	td = curthread;
> :-	if (td->td_critnest == 1) {
> :-		td->td_critnest = 0;
> :-		cpu_critical_exit(td->td_savecrit);
> :-	} else
> :-		td->td_critnest--;
> :+	if (--curthread->td_critnest == 0 && (ipending | spending) != 0)
> :+		unpend();
> : }

ipending here works much as in RELENG_4.  It is ORed into by sched_ithd()
if curthread->td_critnest != 0.  Nothing special is needed for pci
(the ICU masks pending interrupts).

Bruce


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