The patch titled
Subject: dmapool: add alloc/free performance test
has been added to the -mm mm-unstable branch. Its filename is
dmapool-add-alloc-free-performance-test.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/dmapool-add-alloc-free-performance-test.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Keith Busch <kbusch@xxxxxxxxxx>
Subject: dmapool: add alloc/free performance test
Date: Thu, 26 Jan 2023 13:51:14 -0800
Patch series "dmapool enhancements", v4.
Time spent in dma_pool alloc/free increases linearly with the number of
pages backing the pool. We can reduce this to constant time with minor
changes to how free pages are tracked.
This patch (of 12):
Provide a module that allocates and frees many blocks of various sizes and
report how long it takes. This is intended to provide a consistent way to
measure how changes to the dma_pool_alloc/free routines affect timing.
Link: https://lkml.kernel.org/r/20230126215125.4069751-1-kbusch@xxxxxxxx
Link: https://lkml.kernel.org/r/20230126215125.4069751-2-kbusch@xxxxxxxx
Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Tony Battersby <tonyb@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/Kconfig | 9 ++
mm/Makefile | 1
mm/dmapool_test.c | 147 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 157 insertions(+)
--- /dev/null
+++ a/mm/dmapool_test.c
@@ -0,0 +1,147 @@
+#include <linux/device.h>
+#include <linux/dma-map-ops.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+
+#define NR_TESTS (100)
+
+struct dma_pool_pair {
+ dma_addr_t dma;
+ void *v;
+};
+
+struct dmapool_parms {
+ size_t size;
+ size_t align;
+ size_t boundary;
+};
+
+static const struct dmapool_parms pool_parms[] = {
+ { .size = 16, .align = 16, .boundary = 0 },
+ { .size = 64, .align = 64, .boundary = 0 },
+ { .size = 256, .align = 256, .boundary = 0 },
+ { .size = 1024, .align = 1024, .boundary = 0 },
+ { .size = 4096, .align = 4096, .boundary = 0 },
+ { .size = 68, .align = 32, .boundary = 4096 },
+};
+
+static struct dma_pool *pool;
+static struct device test_dev;
+static u64 dma_mask;
+
+static inline int nr_blocks(int size)
+{
+ return clamp_t(int, (PAGE_SIZE / size) * 512, 1024, 8192);
+}
+
+static int dmapool_test_alloc(struct dma_pool_pair *p, int blocks)
+{
+ int i;
+
+ for (i = 0; i < blocks; i++) {
+ p[i].v = dma_pool_alloc(pool, GFP_KERNEL,
+ &p[i].dma);
+ if (!p[i].v)
+ goto pool_fail;
+ }
+
+ for (i = 0; i < blocks; i++)
+ dma_pool_free(pool, p[i].v, p[i].dma);
+
+ return 0;
+
+pool_fail:
+ for (--i; i >= 0; i--)
+ dma_pool_free(pool, p[i].v, p[i].dma);
+ return -ENOMEM;
+}
+
+static int dmapool_test_block(const struct dmapool_parms *parms)
+{
+ int blocks = nr_blocks(parms->size);
+ ktime_t start_time, end_time;
+ struct dma_pool_pair *p;
+ int i, ret;
+
+ p = kcalloc(blocks, sizeof(*p), GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+
+ pool = dma_pool_create("test pool", &test_dev, parms->size,
+ parms->align, parms->boundary);
+ if (!pool) {
+ ret = -ENOMEM;
+ goto free_pairs;
+ }
+
+ start_time = ktime_get();
+ for (i = 0; i < NR_TESTS; i++) {
+ ret = dmapool_test_alloc(p, blocks);
+ if (ret)
+ goto free_pool;
+ if (need_resched())
+ cond_resched();
+ }
+ end_time = ktime_get();
+
+ printk("dmapool test: size:%-4zu align:%-4zu blocks:%-4d time:%llu\n",
+ parms->size, parms->align, blocks,
+ ktime_us_delta(end_time, start_time));
+
+free_pool:
+ dma_pool_destroy(pool);
+free_pairs:
+ kfree(p);
+ return ret;
+}
+
+static void dmapool_test_release(struct device *dev)
+{
+}
+
+static int dmapool_checks(void)
+{
+ int i, ret;
+
+ ret = dev_set_name(&test_dev, "dmapool-test");
+ if (ret)
+ return ret;
+
+ ret = device_register(&test_dev);
+ if (ret) {
+ printk("%s: register failed:%d\n", __func__, ret);
+ goto put_device;
+ }
+
+ test_dev.release = dmapool_test_release;
+ set_dma_ops(&test_dev, NULL);
+ test_dev.dma_mask = &dma_mask;
+ ret = dma_set_mask_and_coherent(&test_dev, DMA_BIT_MASK(64));
+ if (ret) {
+ printk("%s: mask failed:%d\n", __func__, ret);
+ goto del_device;
+ }
+
+ for (i = 0; i < ARRAY_SIZE(pool_parms); i++) {
+ ret = dmapool_test_block(&pool_parms[i]);
+ if (ret)
+ break;
+ }
+
+del_device:
+ device_del(&test_dev);
+put_device:
+ put_device(&test_dev);
+ return ret;
+}
+
+static void dmapool_exit(void)
+{
+}
+
+module_init(dmapool_checks);
+module_exit(dmapool_exit);
+MODULE_LICENSE("GPL");
--- a/mm/Kconfig~dmapool-add-alloc-free-performance-test
+++ a/mm/Kconfig
@@ -1100,6 +1100,15 @@ comment "GUP_TEST needs to have DEBUG_FS
config GUP_GET_PXX_LOW_HIGH
bool
+config DMAPOOL_TEST
+ tristate "Enable a module to run time tests on dma_pool"
+ depends on HAS_DMA
+ help
+ Provides a test module that will allocate and free many blocks of
+ various sizes and report how long it takes. This is intended to
+ provide a consistent way to measure how changes to the
+ dma_pool_alloc/free routines affect performance.
+
config ARCH_HAS_PTE_SPECIAL
bool
--- a/mm/Makefile~dmapool-add-alloc-free-performance-test
+++ a/mm/Makefile
@@ -103,6 +103,7 @@ obj-$(CONFIG_MEMCG) += swap_cgroup.o
endif
obj-$(CONFIG_CGROUP_HUGETLB) += hugetlb_cgroup.o
obj-$(CONFIG_GUP_TEST) += gup_test.o
+obj-$(CONFIG_DMAPOOL_TEST) += dmapool_test.o
obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o
obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o
obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
_
Patches currently in -mm which might be from kbusch@xxxxxxxxxx are
dmapool-add-alloc-free-performance-test.patch
dmapool-move-debug-code-to-own-functions.patch
dmapool-rearrange-page-alloc-failure-handling.patch
dmapool-consolidate-page-initialization.patch
dmapool-simplify-freeing.patch
dmapool-dont-memset-on-free-twice.patch
dmapool-link-blocks-across-pages.patch
dmapool-create-destroy-cleanup.patch
