f18d397e6a
Fix a couple of inconsistencies/problems I found while reviewing the x86_64
genapic code (when I was chasing mysterious eth0 timeouts that would only
trigger if CPU_HOTPLUG is enabled):
- AMD systems defaulted to the slower flat-physical mode instead
of the flat-logical mode. The only restriction on AMD systems
is that they should not use clustered APIC mode.
- removed the CPU hotplug hacks, switching the default for small
systems back from phys-flat to logical-flat. The switching to logical
flat mode on small systems fixed sporadic ethernet driver timeouts i
was getting on a dual-core Athlon64 system:
NETDEV WATCHDOG: eth0: transmit timed out
eth0: Transmit timeout, status 0c 0005 c07f media 80.
eth0: Tx queue start entry 32 dirty entry 28.
eth0: Tx descriptor 0 is 0008a04a. (queue head)
eth0: Tx descriptor 1 is 0008a04a.
eth0: Tx descriptor 2 is 0008a04a.
eth0: Tx descriptor 3 is 0008a04a.
eth0: link up, 100Mbps, full-duplex, lpa 0xC5E1
- The use of '<= 8' was a bug by itself (the valid APIC ids
for logical flat mode go from 0 to 7, not 0 to 8). The new logic
is to use logical flat mode on both AMD and Intel systems, and
to only switch to physical mode when logical mode cannot be used.
If CPU hotplug is racy wrt. APIC shutdown then CPU hotplug needs
fixing, not the whole IRQ system be made inconsistent and slowed
down.
- minor cleanups: simplified some code constructs
build & booted on a couple of AMD and Intel SMP systems.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "Li, Shaohua" <shaohua.li@intel.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
116 lines
2.9 KiB
C
116 lines
2.9 KiB
C
/*
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* Copyright 2004 James Cleverdon, IBM.
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* Subject to the GNU Public License, v.2
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*
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* Generic APIC sub-arch probe layer.
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*
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* Hacked for x86-64 by James Cleverdon from i386 architecture code by
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* Martin Bligh, Andi Kleen, James Bottomley, John Stultz, and
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* James Cleverdon.
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*/
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#include <linux/threads.h>
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#include <linux/cpumask.h>
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#include <linux/string.h>
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#include <linux/kernel.h>
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#include <linux/ctype.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <asm/smp.h>
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#include <asm/ipi.h>
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#if defined(CONFIG_ACPI)
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#include <acpi/acpi_bus.h>
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#endif
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/* which logical CPU number maps to which CPU (physical APIC ID) */
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u8 x86_cpu_to_apicid[NR_CPUS] __read_mostly = { [0 ... NR_CPUS-1] = BAD_APICID };
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EXPORT_SYMBOL(x86_cpu_to_apicid);
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u8 x86_cpu_to_log_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
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extern struct genapic apic_cluster;
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extern struct genapic apic_flat;
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extern struct genapic apic_physflat;
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struct genapic __read_mostly *genapic = &apic_flat;
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/*
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* Check the APIC IDs in bios_cpu_apicid and choose the APIC mode.
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*/
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void __init clustered_apic_check(void)
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{
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int i;
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u8 clusters, max_cluster;
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u8 id;
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u8 cluster_cnt[NUM_APIC_CLUSTERS];
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int max_apic = 0;
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#ifdef CONFIG_ACPI
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/*
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* Some x86_64 machines use physical APIC mode regardless of how many
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* procs/clusters are present (x86_64 ES7000 is an example).
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*/
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if (acpi_gbl_FADT.header.revision > FADT2_REVISION_ID)
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if (acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL) {
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genapic = &apic_cluster;
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goto print;
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}
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#endif
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memset(cluster_cnt, 0, sizeof(cluster_cnt));
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for (i = 0; i < NR_CPUS; i++) {
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id = bios_cpu_apicid[i];
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if (id == BAD_APICID)
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continue;
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if (id > max_apic)
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max_apic = id;
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cluster_cnt[APIC_CLUSTERID(id)]++;
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}
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/*
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* Don't use clustered mode on AMD platforms, default
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* to flat logical mode.
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*/
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if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
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/*
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* Switch to physical flat mode if more than 8 APICs
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* (In the case of 8 CPUs APIC ID goes from 0 to 7):
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*/
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if (max_apic >= 8)
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genapic = &apic_physflat;
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goto print;
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}
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clusters = 0;
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max_cluster = 0;
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for (i = 0; i < NUM_APIC_CLUSTERS; i++) {
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if (cluster_cnt[i] > 0) {
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++clusters;
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if (cluster_cnt[i] > max_cluster)
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max_cluster = cluster_cnt[i];
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}
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}
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/*
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* If we have clusters <= 1 and CPUs <= 8 in cluster 0, then flat mode,
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* else if max_cluster <= 4 and cluster_cnt[15] == 0, clustered logical
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* else physical mode.
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* (We don't use lowest priority delivery + HW APIC IRQ steering, so
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* can ignore the clustered logical case and go straight to physical.)
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*/
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if (clusters <= 1 && max_cluster <= 8 && cluster_cnt[0] == max_cluster)
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genapic = &apic_flat;
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else
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genapic = &apic_cluster;
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print:
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printk(KERN_INFO "Setting APIC routing to %s\n", genapic->name);
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}
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/* Same for both flat and clustered. */
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void send_IPI_self(int vector)
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{
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__send_IPI_shortcut(APIC_DEST_SELF, vector, APIC_DEST_PHYSICAL);
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}
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