Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754298AbbHFAIL (ORCPT ); Wed, 5 Aug 2015 20:08:11 -0400 Received: from mail-pa0-f50.google.com ([209.85.220.50]:33209 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753913AbbHFAIJ (ORCPT ); Wed, 5 Aug 2015 20:08:09 -0400 Date: Thu, 6 Aug 2015 09:08:43 +0900 From: Sergey Senozhatsky To: Dan Streetman Cc: Seth Jennings , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] zswap: change zpool/compressor at runtime Message-ID: <20150806000843.GA3927@swordfish> References: <1438782403-29496-1-git-send-email-ddstreet@ieee.org> <1438782403-29496-4-git-send-email-ddstreet@ieee.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1438782403-29496-4-git-send-email-ddstreet@ieee.org> User-Agent: Mutt/1.5.23+102 (2ca89bed6448) (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6884 Lines: 207 Hi, On (08/05/15 09:46), Dan Streetman wrote: > Update the zpool and compressor parameters to be changeable at runtime. > When changed, a new pool is created with the requested zpool/compressor, > and added as the current pool at the front of the pool list. Previous > pools remain in the list only to remove existing compressed pages from. > The old pool(s) are removed once they become empty. > Sorry, just curious, is this functionality/complication really necessary? How often do you expect people to do that? The way I see it -- a static configuration works just fine: boot, test, re-configure, boot test; compare the results and done. -ss > Signed-off-by: Dan Streetman > --- > mm/zswap.c | 135 +++++++++++++++++++++++++++++++++++++++++++++++++++++++------ > 1 file changed, 122 insertions(+), 13 deletions(-) > > diff --git a/mm/zswap.c b/mm/zswap.c > index f8fcd7e..3eaff21 100644 > --- a/mm/zswap.c > +++ b/mm/zswap.c > @@ -80,23 +80,39 @@ static u64 zswap_duplicate_entry; > static bool zswap_enabled; > module_param_named(enabled, zswap_enabled, bool, 0644); > > -/* Compressor to be used by zswap (fixed at boot for now) */ > +/* Crypto compressor to use */ > #define ZSWAP_COMPRESSOR_DEFAULT "lzo" > -static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT; > -module_param_named(compressor, zswap_compressor, charp, 0444); > - > -/* The maximum percentage of memory that the compressed pool can occupy */ > -static unsigned int zswap_max_pool_percent = 20; > -module_param_named(max_pool_percent, > - zswap_max_pool_percent, uint, 0644); > +static char zswap_compressor[CRYPTO_MAX_ALG_NAME] = ZSWAP_COMPRESSOR_DEFAULT; > +static struct kparam_string zswap_compressor_kparam = { > + .string = zswap_compressor, > + .maxlen = sizeof(zswap_compressor), > +}; > +static int zswap_compressor_param_set(const char *, > + const struct kernel_param *); > +static struct kernel_param_ops zswap_compressor_param_ops = { > + .set = zswap_compressor_param_set, > + .get = param_get_string, > +}; > +module_param_cb(compressor, &zswap_compressor_param_ops, > + &zswap_compressor_kparam, 0644); > > -/* Compressed storage to use */ > +/* Compressed storage zpool to use */ > #define ZSWAP_ZPOOL_DEFAULT "zbud" > -static char *zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT; > -module_param_named(zpool, zswap_zpool_type, charp, 0444); > +static char zswap_zpool_type[32 /* arbitrary */] = ZSWAP_ZPOOL_DEFAULT; > +static struct kparam_string zswap_zpool_kparam = { > + .string = zswap_zpool_type, > + .maxlen = sizeof(zswap_zpool_type), > +}; > +static int zswap_zpool_param_set(const char *, const struct kernel_param *); > +static struct kernel_param_ops zswap_zpool_param_ops = { > + .set = zswap_zpool_param_set, > + .get = param_get_string, > +}; > +module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_kparam, 0644); > > -/* zpool is shared by all of zswap backend */ > -static struct zpool *zswap_pool; > +/* The maximum percentage of memory that the compressed pool can occupy */ > +static unsigned int zswap_max_pool_percent = 20; > +module_param_named(max_pool_percent, zswap_max_pool_percent, uint, 0644); > > /********************************* > * data structures > @@ -161,6 +177,9 @@ static LIST_HEAD(zswap_pools); > /* protects zswap_pools list modification */ > static DEFINE_SPINLOCK(zswap_pools_lock); > > +/* used by param callback function */ > +static bool zswap_init_started; > + > /********************************* > * helpers and fwd declarations > **********************************/ > @@ -661,6 +680,94 @@ static void zswap_pool_put(struct zswap_pool *pool) > kref_put(&pool->kref, __zswap_pool_empty); > } > > +/********************************* > +* param callbacks > +**********************************/ > + > +static int __zswap_param_set(const char *val, const struct kernel_param *kp, > + char *type, char *compressor) > +{ > + struct zswap_pool *pool, *put_pool = NULL; > + char str[kp->str->maxlen], *s; > + int ret; > + > + strlcpy(str, val, kp->str->maxlen); > + s = strim(str); > + > + /* if this is load-time (pre-init) param setting, > + * don't create a pool; that's done during init. > + */ > + if (!zswap_init_started) > + return param_set_copystring(s, kp); > + > + /* no change required */ > + if (!strncmp(kp->str->string, s, kp->str->maxlen)) > + return 0; > + > + if (!type) { > + type = s; > + if (!zpool_has_pool(type)) { > + pr_err("zpool %s not available\n", type); > + return -ENOENT; > + } > + } else if (!compressor) { > + compressor = s; > + if (!crypto_has_comp(compressor, 0, 0)) { > + pr_err("compressor %s not available\n", compressor); > + return -ENOENT; > + } > + } > + > + spin_lock(&zswap_pools_lock); > + > + pool = zswap_pool_find_get(type, compressor); > + if (pool) { > + zswap_pool_debug("using existing", pool); > + list_del_rcu(&pool->list); > + } else { > + spin_unlock(&zswap_pools_lock); > + pool = zswap_pool_create(type, compressor); > + spin_lock(&zswap_pools_lock); > + } > + > + if (pool) > + ret = param_set_copystring(s, kp); > + else > + ret = -EINVAL; > + > + if (!ret) { > + put_pool = zswap_pool_current(); > + list_add_rcu(&pool->list, &zswap_pools); > + } else if (pool) { > + /* add the possibly pre-existing pool to the end of the pools > + * list; if it's new (and empty) then it'll be removed and > + * destroyed by the put after we drop the lock > + */ > + list_add_tail_rcu(&pool->list, &zswap_pools); > + put_pool = pool; > + } > + > + spin_unlock(&zswap_pools_lock); > + > + /* drop the ref from either the old current pool, > + * or the new pool we failed to add > + */ > + if (put_pool) > + zswap_pool_put(put_pool); > + > + return ret; > +} > + > +static int zswap_compressor_param_set(const char *val, > + const struct kernel_param *kp) > +{ > + return __zswap_param_set(val, kp, zswap_zpool_type, NULL); > +} > + > +static int zswap_zpool_param_set(const char *val, > + const struct kernel_param *kp) > +{ > + return __zswap_param_set(val, kp, NULL, zswap_compressor); > } > > /********************************* > @@ -1116,6 +1223,8 @@ static int __init init_zswap(void) > { > struct zswap_pool *pool; > > + zswap_init_started = true; > + > if (zswap_entry_cache_create()) { > pr_err("entry cache creation failed\n"); > goto cache_fail; > -- > 2.1.0 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. 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