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[23.128.96.18]) by mx.google.com with ESMTP id i7si4217878edb.365.2020.05.22.04.28.36; Fri, 22 May 2020 04:29:02 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=qQbEm9ry; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729542AbgEVL0s (ORCPT + 99 others); Fri, 22 May 2020 07:26:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:39890 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728281AbgEVL0s (ORCPT ); Fri, 22 May 2020 07:26:48 -0400 Received: from tleilax.poochiereds.net (68-20-15-154.lightspeed.rlghnc.sbcglobal.net [68.20.15.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A9649206BE; Fri, 22 May 2020 11:26:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590146807; bh=HffsPUQV72xCQs16Zb0KzhZezC5HpjM92iOzJX/rQuY=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=qQbEm9ryVan7BjBF+/jjM9T2zy6S1jtAG5Gjhwxv3k4lAah88e1xbExs/ozNf7APm UcrqlrHUD8AvfIUbKoOLaZzq1TtG/M2Z1Tf8RkNsedvPPK/D9Uo29bXF/Jppza2Vti y2Ari/wR2C3dtcT83vBwhmfuiY+6h+bT9YCTVMDA= Message-ID: <29349a65bc94651a96d2e4a8392e1ca4a00bd2d7.camel@kernel.org> Subject: Re: [PATCH] ceph: show max caps in debugfs caps file From: Jeff Layton To: Yanhu Cao Cc: Ilya Dryomov , ceph-devel , LKML Date: Fri, 22 May 2020 07:26:45 -0400 In-Reply-To: References: <20200521093845.15101-1-gmayyyha@gmail.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.2 (3.36.2-1.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2020-05-22 at 16:27 +0800, Yanhu Cao wrote: > On Thu, May 21, 2020 at 8:51 PM Jeff Layton wrote: > > On Thu, 2020-05-21 at 20:19 +0800, Yanhu Cao wrote: > > > On Thu, May 21, 2020 at 7:09 PM Jeff Layton wrote: > > > > On Thu, 2020-05-21 at 17:38 +0800, Yanhu Cao wrote: > > > > > before > > > > > ------ > > > > > total 1026 > > > > > avail 1024 > > > > > used 2 > > > > > reserved 0 > > > > > min 1024 > > > > > > > > > > after > > > > > ------ > > > > > total 1026 > > > > > avail 1024 > > > > > used 2 > > > > > max 2048 > > > > > reserved 0 > > > > > min 1024 > > > > > > > > > > Signed-off-by: Yanhu Cao > > > > > --- > > > > > fs/ceph/caps.c | 6 ++++-- > > > > > fs/ceph/debugfs.c | 7 ++++--- > > > > > fs/ceph/super.h | 2 +- > > > > > 3 files changed, 9 insertions(+), 6 deletions(-) > > > > > > > > > > diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c > > > > > index 5f3aa4d607de..e2c759a2ef35 100644 > > > > > --- a/fs/ceph/caps.c > > > > > +++ b/fs/ceph/caps.c > > > > > @@ -404,8 +404,8 @@ void ceph_put_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap) > > > > > } > > > > > > > > > > void ceph_reservation_status(struct ceph_fs_client *fsc, > > > > > - int *total, int *avail, int *used, int *reserved, > > > > > - int *min) > > > > > + int *total, int *avail, int *used, int *max, > > > > > + int *reserved, int *min) > > > > > { > > > > > struct ceph_mds_client *mdsc = fsc->mdsc; > > > > > > > > > > @@ -417,6 +417,8 @@ void ceph_reservation_status(struct ceph_fs_client *fsc, > > > > > *avail = mdsc->caps_avail_count; > > > > > if (used) > > > > > *used = mdsc->caps_use_count; > > > > > + if (max) > > > > > + *max = mdsc->caps_use_max; > > > > > > > > Can you lay out what value this will provide? I'm not convinced that > > > > this information is really that helpful: > > > > > > > > mdsc->caps_use_max is just set to the value of the "caps_max" mount > > > > option, and that information is displayed in /proc/mounts if it's not > > > > set to the default. > > > > > > > > What might be more interesting is to track the most recent "max_caps" > > > > value sent by the MDS (see the CEPH_SESSION_RECALL_STATE message > > > > handling). Tracking that would give us a more dynamic view of the > > > > current maximum requested by the MDS, which is often going to be less > > > > than what "caps_max" was set to at mount time. > > > > > > Do you mean the 'mds_recall_max_caps'? which can be set by the MDS. > > > Clients use this value every time to trim caps. > > > > > > There is an option mds_max_caps_per_client which is a soft limit, > > > which is determined by the behavior of the client. > > > and we recently encounter a warning '1 MDSs report oversized > > > cache'(ceph-v12.2.12: mds_cache_memory_limit=64G, used=100G), > > > Therefore, the effect is not good. > > > > > > So we want to know whether the caps held by the client exceed caps_max > > > through the debugfs caps file (default or mount option). > > > > > > > > > > Ok, I doubt this patch is going to tell you what you want to know then. > > There are two limits involved here: > > > > 1/ the limit set by the caps_max mount option for the client > > 2/ a dynamic limit that is managed by the MDS issuing > > CEPH_SESSION_RECALL_STATE messages to the clients (max_caps). > > > > This patch is only going to tell you about the first one, but the second > > one is more interesting to monitor on a long-term basis. > > > > When the mds exceeds its memory limits, it can issue > > CEPH_SESSION_RECALL_STATE messages to the clients, to tell them to > > reduce their own caches to a particular size. Currently we just take > > that value and feed it into ceph_trim_caps and forget about it. > > > > It would probably be useful though to keep track of the most recent > > value issued by the MDS, and print this value as min(mount_option_max, > > max_caps_from_mds). Bonus points if you can help untangle the confusing > > naming of all these values in the process. > > How about this? Add a new field caps_limit(calculated by > session->caps, mds_recall_max_caps, > mds_max_caps_per_client, mds_min_caps_per_client) in ceph_mds_client, > which can be set by ceph_trim_caps. > > struct ceph_mds_client { > ... > - int caps_use_max; /* max used caps */ > + int caps_use_max; /* max used caps, limited > by client */ > + int caps_limit; /* limited by mds */ > ... > } > > int ceph_trim_caps(...) > { > int trim_caps = session->s_nr_caps - max_caps; > + mdsc->caps_limit = max_caps; > ... > } > > if client's caps have no limit, we can track caps_limit. > Don't use min(caps_use_max, caps_limit) because it shows more clearly > whether it is limited by the client or mds. > > e.g. > ---- > total 3112 > avail 1025 > used 2087 > limit 2068 => caps_limit > max 2048 => caps_use_max(mount_option_caps_max) > > trimmed > ------- > total 1943 > avail 1025 > used 918 > limit 918 > max 2048 > > Sure, that'd be fine. The "max" is somewhat redundant info that you can get elsewhere, but printing it here won't hurt anything. > > > > > if (reserved) > > > > > *reserved = mdsc->caps_reserve_count; > > > > > if (min) > > > > > diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c > > > > > index 481ac97b4d25..942004376588 100644 > > > > > --- a/fs/ceph/debugfs.c > > > > > +++ b/fs/ceph/debugfs.c > > > > > @@ -138,16 +138,17 @@ static int caps_show(struct seq_file *s, void *p) > > > > > { > > > > > struct ceph_fs_client *fsc = s->private; > > > > > struct ceph_mds_client *mdsc = fsc->mdsc; > > > > > - int total, avail, used, reserved, min, i; > > > > > + int total, avail, used, max, reserved, min, i; > > > > > struct cap_wait *cw; > > > > > > > > > > - ceph_reservation_status(fsc, &total, &avail, &used, &reserved, &min); > > > > > + ceph_reservation_status(fsc, &total, &avail, &used, &max, > > > > > + &reserved, &min); > > > > > seq_printf(s, "total\t\t%d\n" > > > > > "avail\t\t%d\n" > > > > > "used\t\t%d\n" > > > > > "reserved\t%d\n" > > > > > "min\t\t%d\n\n", > > > > > - total, avail, used, reserved, min); > > > > > + total, avail, used, max, reserved, min); > > > > > seq_printf(s, "ino issued implemented\n"); > > > > > seq_printf(s, "-----------------------------------------------\n"); > > > > > > > > > > diff --git a/fs/ceph/super.h b/fs/ceph/super.h > > > > > index 60aac3aee055..79aa42d9336c 100644 > > > > > --- a/fs/ceph/super.h > > > > > +++ b/fs/ceph/super.h > > > > > @@ -700,7 +700,7 @@ extern void ceph_unreserve_caps(struct ceph_mds_client *mdsc, > > > > > struct ceph_cap_reservation *ctx); > > > > > extern void ceph_reservation_status(struct ceph_fs_client *client, > > > > > int *total, int *avail, int *used, > > > > > - int *reserved, int *min); > > > > > + int *max, int *reserved, int *min); > > > > > > > > > > > > > > > > > > > > > > > -- > > > > Jeff Layton > > > > > > > > -- > > Jeff Layton > > -- Jeff Layton