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116 lines
3.1 KiB
Diff
116 lines
3.1 KiB
Diff
From 66e0ea531f4975fed5899a2cbbfa3986fca40680 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.com>
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Date: Tue, 5 May 2020 15:23:32 +0100
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Subject: [PATCH] zswap: Defer zswap initialisation
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Enabling zswap support in the kernel configuration costs about 1.5MB
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of RAM, even when zswap is not enabled at runtime. This cost can be
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reduced significantly by deferring initialisation (including pool
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creation) until the "enabled" parameter is set to true. There is a
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small cost to this in that some initialisation code has to remain in
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memory after the init phase, just in case they are needed later,
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but the total size increase is negligible.
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See: https://github.com/raspberrypi/linux/pull/3432
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Signed-off-by: Phil Elwell <phil@raspberrypi.com>
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---
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mm/zswap.c | 48 ++++++++++++++++++++++++++++--------------------
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1 file changed, 28 insertions(+), 20 deletions(-)
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--- a/mm/zswap.c
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+++ b/mm/zswap.c
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@@ -564,8 +564,9 @@ error:
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return NULL;
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}
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-static __init struct zswap_pool *__zswap_pool_create_fallback(void)
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+static bool zswap_try_pool_create(void)
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{
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+ struct zswap_pool *pool;
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bool has_comp, has_zpool;
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has_comp = crypto_has_comp(zswap_compressor, 0, 0);
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@@ -599,9 +600,21 @@ static __init struct zswap_pool *__zswap
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}
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if (!has_comp || !has_zpool)
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- return NULL;
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+ return false;
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+
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+ pool = zswap_pool_create(zswap_zpool_type, zswap_compressor);
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+
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+ if (pool) {
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+ pr_info("loaded using pool %s/%s\n", pool->tfm_name,
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+ zpool_get_type(pool->zpool));
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+ list_add(&pool->list, &zswap_pools);
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+ zswap_has_pool = true;
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+ } else {
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+ pr_err("pool creation failed\n");
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+ zswap_enabled = false;
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+ }
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- return zswap_pool_create(zswap_zpool_type, zswap_compressor);
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+ return zswap_enabled;
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}
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static void zswap_pool_destroy(struct zswap_pool *pool)
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@@ -773,16 +786,19 @@ static int zswap_zpool_param_set(const c
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static int zswap_enabled_param_set(const char *val,
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const struct kernel_param *kp)
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{
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+ int ret;
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+
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if (zswap_init_failed) {
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pr_err("can't enable, initialization failed\n");
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return -ENODEV;
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}
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- if (!zswap_has_pool && zswap_init_started) {
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- pr_err("can't enable, no pool configured\n");
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- return -ENODEV;
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- }
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- return param_set_bool(val, kp);
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+ ret = param_set_bool(val, kp);
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+ if (!ret && zswap_enabled && zswap_init_started && !zswap_has_pool)
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+ if (!zswap_try_pool_create())
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+ ret = -ENODEV;
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+
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+ return ret;
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}
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/*********************************
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@@ -1297,7 +1313,6 @@ static void __exit zswap_debugfs_exit(vo
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**********************************/
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static int __init init_zswap(void)
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{
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- struct zswap_pool *pool;
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int ret;
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zswap_init_started = true;
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@@ -1321,20 +1336,13 @@ static int __init init_zswap(void)
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if (ret)
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goto hp_fail;
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- pool = __zswap_pool_create_fallback();
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- if (pool) {
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- pr_info("loaded using pool %s/%s\n", pool->tfm_name,
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- zpool_get_type(pool->zpool));
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- list_add(&pool->list, &zswap_pools);
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- zswap_has_pool = true;
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- } else {
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- pr_err("pool creation failed\n");
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- zswap_enabled = false;
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- }
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-
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frontswap_register_ops(&zswap_frontswap_ops);
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if (zswap_debugfs_init())
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pr_warn("debugfs initialization failed\n");
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+
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+ if (zswap_enabled)
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+ zswap_try_pool_create();
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+
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return 0;
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hp_fail:
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