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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] x86/mwait-idle: add 'preferred-cstates' command line option
commit 9fc9a5c21612993fbd2bb1acdd68d9181ab6f7d2
Author: Artem Bityutskiy <artem.bityutskiy@xxxxxxxxxxxxxxx>
AuthorDate: Thu Oct 13 17:52:36 2022 +0200
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Oct 13 17:52:36 2022 +0200
x86/mwait-idle: add 'preferred-cstates' command line option
On Sapphire Rapids Xeon (SPR) the C1 and C1E states are basically mutually
exclusive - only one of them can be enabled. By default, 'intel_idle' driver
enables C1 and disables C1E. However, some users prefer to use C1E instead
of
C1, because it saves more energy.
This patch adds a new module parameter ('preferred_cstates') for enabling
C1E
and disabling C1. Here is the idea behind it.
1. This option has effect only for "mutually exclusive" C-states like C1 and
C1E on SPR.
2. It does not have any effect on independent C-states, which do not require
other C-states to be disabled (most states on most platforms as of
today).
3. For mutually exclusive C-states, the 'intel_idle' driver always has a
reasonable default, such as enabling C1 on SPR by default. On other
platforms, the default may be different.
4. Users can override the default using the 'preferred_cstates' parameter.
5. The parameter accepts the preferred C-states bit-mask, similarly to the
existing 'states_off' parameter.
6. This parameter is not limited to C1/C1E, and leaves room for supporting
other mutually exclusive C-states, if they come in the future.
Today 'intel_idle' can only be compiled-in, which means that on SPR, in
order
to disable C1 and enable C1E, users should boot with the following kernel
argument: intel_idle.preferred_cstates=4
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@xxxxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Origin: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
da0e58c038e6
Enable C1E (if requested) not only on the BSP's socket / package. Alter
command line option to fit our model, and extend it to also accept
string form arguments.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Release-acked-by: Henry Wang <Henry.Wang@xxxxxxx>
---
docs/misc/xen-command-line.pandoc | 6 ++
xen/arch/x86/cpu/mwait-idle.c | 132 ++++++++++++++++++++++++++++++++------
2 files changed, 119 insertions(+), 19 deletions(-)
diff --git a/docs/misc/xen-command-line.pandoc
b/docs/misc/xen-command-line.pandoc
index 68389843b2..0fbdcb574f 100644
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -1926,6 +1926,12 @@ paging controls access to usermode addresses.
### ple_window (Intel)
> `= <integer>`
+### preferred-cstates (x86)
+> `= ( <integer> | List of ( C1 | C1E | C2 | ... )`
+
+This is a mask of C-states which are to be used preferably. This option is
+applicable only on hardware were certain C-states are exclusive of one another.
+
### psr (Intel)
> `= List of ( cmt:<boolean> | rmid_max:<integer> | cat:<boolean> |
> cos_max:<integer> | cdp:<boolean> )`
diff --git a/xen/arch/x86/cpu/mwait-idle.c b/xen/arch/x86/cpu/mwait-idle.c
index 5d77672f6b..cc62ddf743 100644
--- a/xen/arch/x86/cpu/mwait-idle.c
+++ b/xen/arch/x86/cpu/mwait-idle.c
@@ -82,10 +82,29 @@ boolean_param("mwait-idle", opt_mwait_idle);
static unsigned int mwait_substates;
+/*
+ * Some platforms come with mutually exclusive C-states, so that if one is
+ * enabled, the other C-states must not be used. Example: C1 and C1E on
+ * Sapphire Rapids platform. This parameter allows for selecting the
+ * preferred C-states among the groups of mutually exclusive C-states - the
+ * selected C-states will be registered, the other C-states from the mutually
+ * exclusive group won't be registered. If the platform has no mutually
+ * exclusive C-states, this parameter has no effect.
+ */
+static unsigned int __ro_after_init preferred_states_mask;
+static char __initdata preferred_states[64];
+string_param("preferred-cstates", preferred_states);
+
#define LAPIC_TIMER_ALWAYS_RELIABLE 0xFFFFFFFF
/* Reliable LAPIC Timer States, bit 1 for C1 etc. Default to only C1. */
static unsigned int lapic_timer_reliable_states = (1 << 1);
+enum c1e_promotion {
+ C1E_PROMOTION_PRESERVE,
+ C1E_PROMOTION_ENABLE,
+ C1E_PROMOTION_DISABLE
+};
+
struct idle_cpu {
const struct cpuidle_state *state_table;
@@ -95,7 +114,7 @@ struct idle_cpu {
*/
unsigned long auto_demotion_disable_flags;
bool byt_auto_demotion_disable_flag;
- bool disable_promotion_to_c1e;
+ enum c1e_promotion c1e_promotion;
};
static const struct idle_cpu *icpu;
@@ -924,6 +943,15 @@ static void cf_check byt_auto_demotion_disable(void *dummy)
wrmsrl(MSR_MC6_DEMOTION_POLICY_CONFIG, 0);
}
+static void cf_check c1e_promotion_enable(void *dummy)
+{
+ uint64_t msr_bits;
+
+ rdmsrl(MSR_IA32_POWER_CTL, msr_bits);
+ msr_bits |= 0x2;
+ wrmsrl(MSR_IA32_POWER_CTL, msr_bits);
+}
+
static void cf_check c1e_promotion_disable(void *dummy)
{
u64 msr_bits;
@@ -936,7 +964,7 @@ static void cf_check c1e_promotion_disable(void *dummy)
static const struct idle_cpu idle_cpu_nehalem = {
.state_table = nehalem_cstates,
.auto_demotion_disable_flags = NHM_C1_AUTO_DEMOTE | NHM_C3_AUTO_DEMOTE,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_atom = {
@@ -954,64 +982,64 @@ static const struct idle_cpu idle_cpu_lincroft = {
static const struct idle_cpu idle_cpu_snb = {
.state_table = snb_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_byt = {
.state_table = byt_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
.byt_auto_demotion_disable_flag = true,
};
static const struct idle_cpu idle_cpu_cht = {
.state_table = cht_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
.byt_auto_demotion_disable_flag = true,
};
static const struct idle_cpu idle_cpu_ivb = {
.state_table = ivb_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_ivt = {
.state_table = ivt_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_hsw = {
.state_table = hsw_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_bdw = {
.state_table = bdw_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_skl = {
.state_table = skl_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_skx = {
.state_table = skx_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_icx = {
- .state_table = icx_cstates,
- .disable_promotion_to_c1e = true,
+ .state_table = icx_cstates,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static struct idle_cpu __read_mostly idle_cpu_spr = {
.state_table = spr_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_avn = {
.state_table = avn_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_knl = {
@@ -1020,17 +1048,17 @@ static const struct idle_cpu idle_cpu_knl = {
static const struct idle_cpu idle_cpu_bxt = {
.state_table = bxt_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_dnv = {
.state_table = dnv_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
static const struct idle_cpu idle_cpu_snr = {
.state_table = snr_cstates,
- .disable_promotion_to_c1e = true,
+ .c1e_promotion = C1E_PROMOTION_DISABLE,
};
#define ICPU(model, cpu) \
@@ -1240,6 +1268,25 @@ static void __init skx_idle_state_table_update(void)
}
}
+/*
+ * spr_idle_state_table_update - Adjust Sapphire Rapids idle states table.
+ */
+static void __init spr_idle_state_table_update(void)
+{
+ /* Check if user prefers C1E over C1. */
+ if (preferred_states_mask & BIT(2, U)) {
+ if (preferred_states_mask & BIT(1, U))
+ /* Both can't be enabled, stick to the defaults. */
+ return;
+
+ spr_cstates[0].flags |= CPUIDLE_FLAG_DISABLED;
+ spr_cstates[1].flags &= ~CPUIDLE_FLAG_DISABLED;
+
+ /* Request enabling C1E using the "C1E promotion" bit. */
+ idle_cpu_spr.c1e_promotion = C1E_PROMOTION_ENABLE;
+ }
+}
+
/*
* mwait_idle_state_table_update()
*
@@ -1261,6 +1308,9 @@ static void __init mwait_idle_state_table_update(void)
case INTEL_FAM6_SKYLAKE_X:
skx_idle_state_table_update();
break;
+ case INTEL_FAM6_SAPPHIRERAPIDS_X:
+ spr_idle_state_table_update();
+ break;
}
}
@@ -1268,6 +1318,7 @@ static int __init mwait_idle_probe(void)
{
unsigned int eax, ebx, ecx;
const struct x86_cpu_id *id = x86_match_cpu(intel_idle_ids);
+ const char *str;
if (!id) {
pr_debug(PREFIX "does not run on family %d model %d\n",
@@ -1309,6 +1360,39 @@ static int __init mwait_idle_probe(void)
pr_debug(PREFIX "lapic_timer_reliable_states %#x\n",
lapic_timer_reliable_states);
+ str = preferred_states;
+ if (isdigit(str[0]))
+ preferred_states_mask = simple_strtoul(str, &str, 0);
+ else if (str[0])
+ {
+ const char *ss;
+
+ do {
+ const struct cpuidle_state *state = icpu->state_table;
+ unsigned int bit = 1;
+
+ ss = strchr(str, ',');
+ if (!ss)
+ ss = strchr(str, '\0');
+
+ for (; state->name[0]; ++state) {
+ bit <<= 1;
+ if (!cmdline_strcmp(str, state->name)) {
+ preferred_states_mask |= bit;
+ break;
+ }
+ }
+ if (!state->name[0])
+ break;
+
+ str = ss + 1;
+ } while (*ss);
+
+ str -= str == ss + 1;
+ }
+ if (str[0])
+ printk("unrecognized \"preferred-cstates=%s\"\n", str);
+
mwait_idle_state_table_update();
return 0;
@@ -1400,8 +1484,18 @@ static int cf_check mwait_idle_cpu_init(
if (icpu->byt_auto_demotion_disable_flag)
on_selected_cpus(cpumask_of(cpu), byt_auto_demotion_disable,
NULL, 1);
- if (icpu->disable_promotion_to_c1e)
+ switch (icpu->c1e_promotion) {
+ case C1E_PROMOTION_DISABLE:
on_selected_cpus(cpumask_of(cpu), c1e_promotion_disable, NULL,
1);
+ break;
+
+ case C1E_PROMOTION_ENABLE:
+ on_selected_cpus(cpumask_of(cpu), c1e_promotion_enable, NULL,
1);
+ break;
+
+ case C1E_PROMOTION_PRESERVE:
+ break;
+ }
return NOTIFY_DONE;
}
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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