From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZq0m/Tndx3sBk3ZMIqJ1i4Q7hPLVAuOd4E4asF/RqQ4mJLJXLAwtz8Ce+eH1ewClvw4HUq8 ARC-Seal: i=1; a=rsa-sha256; t=1525392524; cv=none; d=google.com; s=arc-20160816; b=fCoigCSxdOOJQAJBKl0KU5g39Lvp7jG6RUMgM7KYz+P6O2z7Fg6xfMmA9TNpUcgvEg o2MqsJHJ2SVKgQi4nGt0izsUhf+n2ffbvP6qmNHEdYo7UFkp77ojgUHe9iAiK0EZgt/O bd/naPtqhDLZoUPEc8q6U6MrA+t87yRyUKhS+DaMsumOEehVxBLjB4rbzbvhVxBUM5yO FTypWWWWfb+8cXTmFjGuH3mOrzx3y+s7cwAtLNUN1NlH/Da9puqVKnRXSkOfRoZ//Zke VwzenxlcOcQ2jAEZoFZAfXgeLEtGwg7fMkYJdUItwFh0LoatPG8SqYcW9TPRhS19tjle 7sQw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:message-id:references:in-reply-to:subject:cc:date:to :from:arc-authentication-results; bh=BZweXGY/nQWibSnT80PqVDW538mHG1KN4xEUR29FtL8=; b=knlOgbY5LF+RESCl44oX+7a7NLVbSFTjuU1Ll1HRdOs9hF4PuvNvOnNnqG69xbyghe zcdxicI5Tg4+7jH2sxxVXOihB35xYX1indcavyKo6wBAak3b+UdotD9aGAU0F5EJ9x0/ z5FvMx6ED78MTY00Rg/igHDoMdbisxvoB+3ElkMlJqjVz25eEkAoBTbMcrxGQX/QZiNw dvE8e7Zk2Jt79UJRKVxUp2qdh7grY4u6uMLFEXSfwopaeDBfgTDo2IO9gXZ/1lbjacrY 3lDUyWuWNFZHF5EyAZ5NfK5NmBUVKpAAis9VaQVlGvOdgVwB0MLmkdDvcM4Jsdc5iLw6 epkQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of neilb@suse.com designates 195.135.220.15 as permitted sender) smtp.mailfrom=neilb@suse.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of neilb@suse.com designates 195.135.220.15 as permitted sender) smtp.mailfrom=neilb@suse.com From: NeilBrown To: "Dilger\, Andreas" Date: Fri, 04 May 2018 10:08:35 +1000 Cc: "Drokin\, Oleg" , Greg Kroah-Hartman , James Simmons , "Linux Kernel Mailing List" , Lustre Development List Subject: Re: [PATCH 03/10] staging: lustre: lu_object: discard extra lru count. In-Reply-To: References: <152514658325.17843.11455067361317157487.stgit@noble> <152514675893.17843.8396665070911641266.stgit@noble> Message-ID: <87k1skffjw.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1599232334415255756?= X-GMAIL-MSGID: =?utf-8?q?1599489991692535119?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue, May 01 2018, Dilger, Andreas wrote: > On Apr 30, 2018, at 21:52, NeilBrown wrote: >>=20 >> lu_object maintains 2 lru counts. >> One is a per-bucket lsb_lru_len. >> The other is the per-cpu ls_lru_len_counter. >>=20 >> The only times the per-bucket counters are use are: >> - a debug message when an object is added >> - in lu_site_stats_get when all the counters are combined. >>=20 >> The debug message is not essential, and the per-cpu counter >> can be used to get the combined total. >>=20 >> So discard the per-bucket lsb_lru_len. >>=20 >> Signed-off-by: NeilBrown > > Looks reasonable, though it would also be possible to fix the percpu > functions rather than adding a workaround in this code. It would be possibly to change percpu_counter_read_positive() to take a const (and we should), but thanks to you highlighting this I realized that I should be using percpu_counter_sum_positive(), to read across all per-cpu counters. That takes a spinlock so it would be a much harder sell to get it to accept a const pointer. Thanks, NeilBrown > > Reviewed-by: Andreas Dilger > >> --- >> drivers/staging/lustre/lustre/obdclass/lu_object.c | 24 ++++++++------= ------ >> 1 file changed, 9 insertions(+), 15 deletions(-) >>=20 >> diff --git a/drivers/staging/lustre/lustre/obdclass/lu_object.c b/driver= s/staging/lustre/lustre/obdclass/lu_object.c >> index 2a8a25d6edb5..2bf089817157 100644 >> --- a/drivers/staging/lustre/lustre/obdclass/lu_object.c >> +++ b/drivers/staging/lustre/lustre/obdclass/lu_object.c >> @@ -57,10 +57,6 @@ >> #include >>=20 >> struct lu_site_bkt_data { >> - /** >> - * number of object in this bucket on the lsb_lru list. >> - */ >> - long lsb_lru_len; >> /** >> * LRU list, updated on each access to object. Protected by >> * bucket lock of lu_site::ls_obj_hash. >> @@ -187,10 +183,9 @@ void lu_object_put(const struct lu_env *env, struct= lu_object *o) >> if (!lu_object_is_dying(top)) { >> LASSERT(list_empty(&top->loh_lru)); >> list_add_tail(&top->loh_lru, &bkt->lsb_lru); >> - bkt->lsb_lru_len++; >> percpu_counter_inc(&site->ls_lru_len_counter); >> - CDEBUG(D_INODE, "Add %p to site lru. hash: %p, bkt: %p, lru_len: %ld\= n", >> - o, site->ls_obj_hash, bkt, bkt->lsb_lru_len); >> + CDEBUG(D_INODE, "Add %p to site lru. hash: %p, bkt: %p\n", >> + o, site->ls_obj_hash, bkt); >> cfs_hash_bd_unlock(site->ls_obj_hash, &bd, 1); >> return; >> } >> @@ -238,7 +233,6 @@ void lu_object_unhash(const struct lu_env *env, stru= ct lu_object *o) >>=20 >> list_del_init(&top->loh_lru); >> bkt =3D cfs_hash_bd_extra_get(obj_hash, &bd); >> - bkt->lsb_lru_len--; >> percpu_counter_dec(&site->ls_lru_len_counter); >> } >> cfs_hash_bd_del_locked(obj_hash, &bd, &top->loh_hash); >> @@ -422,7 +416,6 @@ int lu_site_purge_objects(const struct lu_env *env, = struct lu_site *s, >> cfs_hash_bd_del_locked(s->ls_obj_hash, >> &bd2, &h->loh_hash); >> list_move(&h->loh_lru, &dispose); >> - bkt->lsb_lru_len--; >> percpu_counter_dec(&s->ls_lru_len_counter); >> if (did_sth =3D=3D 0) >> did_sth =3D 1; >> @@ -621,7 +614,6 @@ static struct lu_object *htable_lookup(struct lu_sit= e *s, >> lprocfs_counter_incr(s->ls_stats, LU_SS_CACHE_HIT); >> if (!list_empty(&h->loh_lru)) { >> list_del_init(&h->loh_lru); >> - bkt->lsb_lru_len--; >> percpu_counter_dec(&s->ls_lru_len_counter); >> } >> return lu_object_top(h); >> @@ -1834,19 +1826,21 @@ struct lu_site_stats { >> unsigned int lss_busy; >> }; >>=20 >> -static void lu_site_stats_get(struct cfs_hash *hs, >> +static void lu_site_stats_get(const struct lu_site *s, >> struct lu_site_stats *stats, int populated) >> { >> + struct cfs_hash *hs =3D s->ls_obj_hash; >> struct cfs_hash_bd bd; >> unsigned int i; >> + /* percpu_counter_read_positive() won't accept a const pointer */ >> + struct lu_site *s2 =3D (struct lu_site *)s; > > It would seem worthwhile to change the percpu_counter_read_positive() and > percpu_counter_read() arguments to be "const struct percpu_counter *fbc", > rather than doing this cast here. I can't see any reason that would be b= ad, > since both implementations just access fbc->count, and do not modify anyt= hing. > >> + stats->lss_busy +=3D cfs_hash_size_get(hs) - >> + percpu_counter_read_positive(&s2->ls_lru_len_counter); >> cfs_hash_for_each_bucket(hs, &bd, i) { >> - struct lu_site_bkt_data *bkt =3D cfs_hash_bd_extra_get(hs, &bd); >> struct hlist_head *hhead; >>=20 >> cfs_hash_bd_lock(hs, &bd, 1); >> - stats->lss_busy +=3D >> - cfs_hash_bd_count_get(&bd) - bkt->lsb_lru_len; >> stats->lss_total +=3D cfs_hash_bd_count_get(&bd); >> stats->lss_max_search =3D max((int)stats->lss_max_search, >> cfs_hash_bd_depmax_get(&bd)); >> @@ -2039,7 +2033,7 @@ int lu_site_stats_print(const struct lu_site *s, s= truct seq_file *m) >> struct lu_site_stats stats; >>=20 >> memset(&stats, 0, sizeof(stats)); >> - lu_site_stats_get(s->ls_obj_hash, &stats, 1); >> + lu_site_stats_get(s, &stats, 1); >>=20 >> seq_printf(m, "%d/%d %d/%ld %d %d %d %d %d %d %d\n", >> stats.lss_busy, >>=20 >>=20 > > Cheers, Andreas > -- > Andreas Dilger > Lustre Principal Architect > Intel Corporation --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlrrpIQACgkQOeye3VZi gbkCeRAAxIt9W56dEceDCtTHA4FpcsAytHCbbwT3JbRZDqYqOpzXXJw0N8iJTgz5 RQSafAMTSq6Ht5PuT1NRJQlr5FFYaDHZoSwUXpMhrcKiYnjEoL5vLNXDFSGMqAAT sSRlF/bDBIVPZ0aqCV1kRo8MQhCodl8Gwx6X5AHqhGLkIZrIQqSyV7NhX4hk+PKJ OGV3Db4pQOu5SpwIhO8zHP7GkWkuIeKf+MoSL72k1KHs026cXeM/wVTuHC4XjQ2b TXQwg5CwChAXpOyjkvQEke8KCiMhrfuBLpreiMJCzuTcki3oEvhnEpTxHCgXKMOO DzdP+Pg/edfQQeFDDf0H61TEcr08+7+D42K+abZ8V7AE+CeN04VVtmXNdYa2VWGr QfEEP7jNwkBfjhGUXPcKePpJvwzduKRQ8dY6ZXw2oerf0kVyTpGPF7G3wSWZ8mVN TnN5c3U8Ozt1yVBBeQlxQFzNRjiRbAC4pFXGMSvzB/zvte4inZfyz5ypvKhy6U0w ub1thbiqTa0/G0TBLPencLepUWH1EmbfYWa8j7ZGR9IqGQQKHo+JkIZfzwaBSJvH bULC6waZUFHwCmpCKlxNZC6DvqPo/oDcPd+XKHXXZ1y5F28OFTrtGNECDeGJO4Od nKaD7ON60yW2rdNeakbVczxerkiwnDjvTRzzTfVEQzBsNmsc9qw= =p/N0 -----END PGP SIGNATURE----- --=-=-=--