Thread (1 message) 1 message, 1 author, 2013-07-16
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[PATCH] zram percpu implementation

From: mani <hidden>
Date: 2013-07-16 18:57:34
Also in: linux-fsdevel 

From 4d52438c9640e64203c2434a74e2abfe3a4168ec Mon Sep 17 00:00:00 2001
From: Manish Sharma <redacted>
Date: Thu, 4 Apr 2013 10:32:08 +0530
Subject: [PATCH] zram percpu implementation

This patch will create a percpu structures compression algo.
1. Takes extra memory for workspace buffers.
I haven't seen any performance gain with this need to find the
root cause.
---
 drivers/staging/zram/zram_drv.c |   69
+++++++++++++++++++++++++++++++--------
 drivers/staging/zram/zram_drv.h |    9 +++--
 2 files changed, 62 insertions(+), 16 deletions(-)

diff --git a/drivers/staging/zram/zram_drv.c
b/drivers/staging/zram/zram_drv.c
index 071e058..5aef8cc 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -271,9 +271,10 @@ static int zram_bvec_write(struct zram *zram, struct
bio_vec *bvec, u32 index,
    unsigned long handle;
    struct page *page;
    unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
+    struct zram_buff *zbuff;

    page = bvec->bv_page;
-    src = zram->compress_buffer;
+/*    src = zram->compress_buffer; */

    if (is_partial_io(bvec)) {
        /*
@@ -318,9 +319,11 @@ static int zram_bvec_write(struct zram *zram, struct
bio_vec *bvec, u32 index,
        ret = 0;
        goto out;
    }
+    zbuff = get_cpu_ptr(zram->zbuff);
+    src = zbuff->compress_buffer;

    ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
-                   zram->compress_workmem);
+                zbuff->compress_workmem);

    if (!is_partial_io(bvec)) {
        kunmap_atomic(user_mem);
@@ -329,6 +332,7 @@ static int zram_bvec_write(struct zram *zram, struct
bio_vec *bvec, u32 index,
    }

    if (unlikely(ret != LZO_E_OK)) {
+        put_cpu_ptr(zram->zbuff);
        pr_err("Compression failed! err=%d\n", ret);
        goto out;
    }
@@ -343,6 +347,7 @@ static int zram_bvec_write(struct zram *zram, struct
bio_vec *bvec, u32 index,

    handle = zs_malloc(zram->mem_pool, clen);
    if (!handle) {
+        put_cpu_ptr(zram->zbuff);
        pr_info("Error allocating memory for compressed "
            "page: %u, size=%zu\n", index, clen);
        ret = -ENOMEM;
@@ -366,7 +371,7 @@ static int zram_bvec_write(struct zram *zram, struct
bio_vec *bvec, u32 index,
    zram_stat_inc(&zram->stats.pages_stored);
    if (clen <= PAGE_SIZE / 2)
        zram_stat_inc(&zram->stats.good_compress);
-
+    put_cpu_ptr(zram->zbuff);
 out:
    if (is_partial_io(bvec))
        kfree(uncmem);
@@ -382,13 +387,13 @@ static int zram_bvec_rw(struct zram *zram, struct
bio_vec *bvec, u32 index,
    int ret;

    if (rw == READ) {
-        down_read(&zram->lock);
+/*        down_read(&zram->lock);*/
        ret = zram_bvec_read(zram, bvec, index, offset, bio);
-        up_read(&zram->lock);
+/*        up_read(&zram->lock);*/
    } else {
-        down_write(&zram->lock);
+/*        down_write(&zram->lock);*/
        ret = zram_bvec_write(zram, bvec, index, offset);
-        up_write(&zram->lock);
+/*        up_write(&zram->lock);*/
    }

    return ret;
@@ -506,15 +511,17 @@ error:
 void __zram_reset_device(struct zram *zram)
 {
    size_t index;
+    int cpu = 0;
+    struct zram_buff *zbuff;

    zram->init_done = 0;

    /* Free various per-device buffers */
-    kfree(zram->compress_workmem);
+/*    kfree(zram->compress_workmem);
    free_pages((unsigned long)zram->compress_buffer, 1);

    zram->compress_workmem = NULL;
-    zram->compress_buffer = NULL;
+    zram->compress_buffer = NULL; */

    /* Free all pages that are still in this zram device */
    for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
@@ -524,10 +531,17 @@ void __zram_reset_device(struct zram *zram)

        zs_free(zram->mem_pool, handle);
    }
-
+    for_each_possible_cpu(cpu) {
+        zbuff = per_cpu_ptr(zram->zbuff, cpu);
+        if (zbuff->compress_workmem)
+            kfree(zbuff->compress_workmem);
+        if (zbuff->compress_buffer)
+            free_pages((unsigned long)zbuff->compress_buffer, 1);
+    }
    vfree(zram->table);
    zram->table = NULL;
-
+    free_percpu(zram->zbuff);
+    zram->zbuff = NULL;
    zs_destroy_pool(zram->mem_pool);
    zram->mem_pool = NULL;

@@ -548,6 +562,8 @@ int zram_init_device(struct zram *zram)
 {
    int ret;
    size_t num_pages;
+    int cpu = 0;
+    struct zram_buff *zbuff;

    down_write(&zram->init_lock);

@@ -558,19 +574,44 @@ int zram_init_device(struct zram *zram)

    zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);

-    zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
+/*    zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
    if (!zram->compress_workmem) {
        pr_err("Error allocating compressor working memory!\n");
        ret = -ENOMEM;
        goto fail_no_table;
+    } */
+    zram->zbuff = alloc_percpu(struct zram_buff);
+    if (!zram->zbuff) {
+        printk(KERN_EMERG"ERROR: per cpu zbuff allocation failed\n");
+        mutex_unlock(&zram->init_lock);
+        return -ENOMEM;
    }

-    zram->compress_buffer =
+
+/*    zram->compress_buffer =
        (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
    if (!zram->compress_buffer) {
        pr_err("Error allocating compressor buffer space\n");
        ret = -ENOMEM;
        goto fail_no_table;
+    } */
+
+    for_each_possible_cpu(cpu) {
+        printk(KERN_EMERG"[%s] Initializing for each core %d\n", cpu);
+        zbuff = per_cpu_ptr(zram->zbuff, cpu);
+        zbuff->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
+        if (!zbuff->compress_workmem) {
+               pr_err("Error allocating compressor working memory!\n");
+            ret = -ENOMEM;
+            goto fail;
+        }
+
+        zbuff->compress_buffer = (void *)__get_free_pages(__GFP_ZERO, 1);
+        if (!zbuff->compress_buffer) {
+            pr_err("Error allocating compressor buffer space\n");
+            ret = -ENOMEM;
+            goto fail;
+        }
    }

    num_pages = zram->disksize >> PAGE_SHIFT;
@@ -628,7 +669,7 @@ static int create_device(struct zram *zram, int
device_id)
 {
    int ret = 0;

-    init_rwsem(&zram->lock);
+/*    init_rwsem(&zram->lock);*/
    init_rwsem(&zram->init_lock);
    spin_lock_init(&zram->stat64_lock);

diff --git a/drivers/staging/zram/zram_drv.h
b/drivers/staging/zram/zram_drv.h
index df2eec4..9adca81 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -17,6 +17,7 @@

 #include <linux/spinlock.h>
 #include <linux/mutex.h>
+#include <linux/percpu.h>

 #include "../zsmalloc/zsmalloc.h"

@@ -86,10 +87,14 @@ struct zram_stats {
    u32 bad_compress;    /* % of pages with compression ratio>=75% */
 };

-struct zram {
-    struct zs_pool *mem_pool;
+struct zram_buff {
    void *compress_workmem;
    void *compress_buffer;
+};
+
+struct zram {
+    struct zs_pool *mem_pool;
+    struct zram_buff __percpu *zbuff;
    struct table *table;
    spinlock_t stat64_lock;    /* protect 64-bit stats */
    struct rw_semaphore lock; /* protect compression buffers and table
--
1.7.9.5
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