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authorDavid Jander <david@protonic.nl>2022-05-24 11:18:08 +0200
committerMark Brown <broonie@kernel.org>2022-06-06 12:41:31 +0100
commit6598b91b5ac32bc756d7c3000a31f775d4ead1c4 (patch)
tree9bf8f2c1b9739bdbe5cf57ad90d6f336ceb99e09 /include/linux/spi
parentb658be56e867061a0d5496e837f350974ada5c89 (diff)
spi: spi.c: Convert statistics to per-cpu u64_stats_t
This change gives a dramatic performance improvement in the hot path, since many costly spin_lock_irqsave() calls can be avoided. On an i.MX8MM system with a MCP2518FD CAN controller connected via SPI, the time the driver takes to handle interrupts, or in other words the time the IRQ line of the CAN controller stays low is mainly dominated by the time it takes to do 3 relatively short sync SPI transfers. The effect of this patch is a reduction of this time from 136us down to only 98us. Suggested-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David Jander <david@protonic.nl> Link: https://lore.kernel.org/r/20220524091808.2269898-1-david@protonic.nl Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'include/linux/spi')
-rw-r--r--include/linux/spi/spi.h52
1 files changed, 29 insertions, 23 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index eadfd3ba3cbc..eac8d3caf954 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -17,6 +17,7 @@
#include <uapi/linux/spi/spi.h>
#include <linux/acpi.h>
+#include <linux/u64_stats_sync.h>
struct dma_chan;
struct software_node;
@@ -59,37 +60,42 @@ extern struct bus_type spi_bus_type;
* maxsize limit
*/
struct spi_statistics {
- spinlock_t lock; /* lock for the whole structure */
+ struct u64_stats_sync syncp;
- unsigned long messages;
- unsigned long transfers;
- unsigned long errors;
- unsigned long timedout;
+ u64_stats_t messages;
+ u64_stats_t transfers;
+ u64_stats_t errors;
+ u64_stats_t timedout;
- unsigned long spi_sync;
- unsigned long spi_sync_immediate;
- unsigned long spi_async;
+ u64_stats_t spi_sync;
+ u64_stats_t spi_sync_immediate;
+ u64_stats_t spi_async;
- unsigned long long bytes;
- unsigned long long bytes_rx;
- unsigned long long bytes_tx;
+ u64_stats_t bytes;
+ u64_stats_t bytes_rx;
+ u64_stats_t bytes_tx;
#define SPI_STATISTICS_HISTO_SIZE 17
- unsigned long transfer_bytes_histo[SPI_STATISTICS_HISTO_SIZE];
+ u64_stats_t transfer_bytes_histo[SPI_STATISTICS_HISTO_SIZE];
- unsigned long transfers_split_maxsize;
+ u64_stats_t transfers_split_maxsize;
};
-#define SPI_STATISTICS_ADD_TO_FIELD(stats, field, count) \
- do { \
- unsigned long flags; \
- spin_lock_irqsave(&(stats)->lock, flags); \
- (stats)->field += count; \
- spin_unlock_irqrestore(&(stats)->lock, flags); \
+#define SPI_STATISTICS_ADD_TO_FIELD(pcpu_stats, field, count) \
+ do { \
+ struct spi_statistics *__lstats = this_cpu_ptr(pcpu_stats); \
+ u64_stats_update_begin(&__lstats->syncp); \
+ u64_stats_add(&__lstats->field, count); \
+ u64_stats_update_end(&__lstats->syncp); \
} while (0)
-#define SPI_STATISTICS_INCREMENT_FIELD(stats, field) \
- SPI_STATISTICS_ADD_TO_FIELD(stats, field, 1)
+#define SPI_STATISTICS_INCREMENT_FIELD(pcpu_stats, field) \
+ do { \
+ struct spi_statistics *__lstats = this_cpu_ptr(pcpu_stats); \
+ u64_stats_update_begin(&__lstats->syncp); \
+ u64_stats_inc(&__lstats->field); \
+ u64_stats_update_end(&__lstats->syncp); \
+ } while (0)
/**
* struct spi_delay - SPI delay information
@@ -194,7 +200,7 @@ struct spi_device {
struct spi_delay cs_inactive;
/* the statistics */
- struct spi_statistics statistics;
+ struct spi_statistics __percpu *pcpu_statistics;
/*
* likely need more hooks for more protocol options affecting how
@@ -647,7 +653,7 @@ struct spi_controller {
s8 max_native_cs;
/* statistics */
- struct spi_statistics statistics;
+ struct spi_statistics __percpu *pcpu_statistics;
/* DMA channels for use with core dmaengine helpers */
struct dma_chan *dma_tx;