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ptp: Speed up vclock lookup

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ptp_convert_timestamp() is called in the RX path of network messages.
The current implementation takes ~5000ns on 1.2GHz A53. This is too much
for the hot path of packet processing.

Introduce hash table for fast vclock lookup in ptp_convert_timestamp().
The execution time of ptp_convert_timestamp() is reduced to ~700ns on
1.2GHz A53.

Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Gerhard Engleder 2022-05-06 22:01:41 +02:00 committed by Paolo Abeni
parent 97dc7cd92a
commit fcf308e509
2 changed files with 50 additions and 21 deletions
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1
drivers/ptp/ptp_private.h
View File

@ -63,6 +63,7 @@ struct ptp_vclock {
struct ptp_clock *pclock;
struct ptp_clock_info info;
struct ptp_clock *clock;
struct hlist_node vclock_hash_node;
struct cyclecounter cc;
struct timecounter tc;
spinlock_t lock; /* protects tc/cc */

70
drivers/ptp/ptp_vclock.c
View File

@ -5,6 +5,7 @@
* Copyright 2021 NXP
*/
#include <linux/slab.h>
#include <linux/hashtable.h>
#include "ptp_private.h"
#define PTP_VCLOCK_CC_SHIFT 31
@ -13,6 +14,32 @@
#define PTP_VCLOCK_FADJ_DENOMINATOR 15625ULL
#define PTP_VCLOCK_REFRESH_INTERVAL (HZ * 2)
/* protects vclock_hash addition/deletion */
static DEFINE_SPINLOCK(vclock_hash_lock);
static DEFINE_READ_MOSTLY_HASHTABLE(vclock_hash, 8);
static void ptp_vclock_hash_add(struct ptp_vclock *vclock)
{
spin_lock(&vclock_hash_lock);
hlist_add_head_rcu(&vclock->vclock_hash_node,
&vclock_hash[vclock->clock->index % HASH_SIZE(vclock_hash)]);
spin_unlock(&vclock_hash_lock);
}
static void ptp_vclock_hash_del(struct ptp_vclock *vclock)
{
spin_lock(&vclock_hash_lock);
hlist_del_init_rcu(&vclock->vclock_hash_node);
spin_unlock(&vclock_hash_lock);
synchronize_rcu();
}
static int ptp_vclock_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
{
struct ptp_vclock *vclock = info_to_vclock(ptp);
@ -176,6 +203,8 @@ struct ptp_vclock *ptp_vclock_register(struct ptp_clock *pclock)
snprintf(vclock->info.name, PTP_CLOCK_NAME_LEN, "ptp%d_virt",
pclock->index);
INIT_HLIST_NODE(&vclock->vclock_hash_node);
spin_lock_init(&vclock->lock);
vclock->clock = ptp_clock_register(&vclock->info, &pclock->dev);
@ -187,11 +216,15 @@ struct ptp_vclock *ptp_vclock_register(struct ptp_clock *pclock)
timecounter_init(&vclock->tc, &vclock->cc, 0);
ptp_schedule_worker(vclock->clock, PTP_VCLOCK_REFRESH_INTERVAL);
ptp_vclock_hash_add(vclock);
return vclock;
}
void ptp_vclock_unregister(struct ptp_vclock *vclock)
{
ptp_vclock_hash_del(vclock);
ptp_clock_unregister(vclock->clock);
kfree(vclock);
}
@ -234,34 +267,29 @@ EXPORT_SYMBOL(ptp_get_vclocks_index);
ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, int vclock_index)
{
char name[PTP_CLOCK_NAME_LEN] = "";
unsigned int hash = vclock_index % HASH_SIZE(vclock_hash);
struct ptp_vclock *vclock;
struct ptp_clock *ptp;
unsigned long flags;
struct device *dev;
u64 ns;
snprintf(name, PTP_CLOCK_NAME_LEN, "ptp%d", vclock_index);
dev = class_find_device_by_name(ptp_class, name);
if (!dev)
return 0;
ptp = dev_get_drvdata(dev);
if (!ptp->is_virtual_clock) {
put_device(dev);
return 0;
}
vclock = info_to_vclock(ptp->info);
u64 vclock_ns = 0;
ns = ktime_to_ns(*hwtstamp);
spin_lock_irqsave(&vclock->lock, flags);
ns = timecounter_cyc2time(&vclock->tc, ns);
spin_unlock_irqrestore(&vclock->lock, flags);
rcu_read_lock();
put_device(dev);
return ns_to_ktime(ns);
hlist_for_each_entry_rcu(vclock, &vclock_hash[hash], vclock_hash_node) {
if (vclock->clock->index != vclock_index)
continue;
spin_lock_irqsave(&vclock->lock, flags);
vclock_ns = timecounter_cyc2time(&vclock->tc, ns);
spin_unlock_irqrestore(&vclock->lock, flags);
break;
}
rcu_read_unlock();
return ns_to_ktime(vclock_ns);
}
EXPORT_SYMBOL(ptp_convert_timestamp);
#endif