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Mon, 17 Jul 2023 15:58:56 -0700 (PDT) MIME-Version: 1.0 References: <20230714194610.828210-1-hannes@cmpxchg.org> <20230717141250.GA866068@cmpxchg.org> <901409ed-504b-9500-54d8-e42f832e07b0@suse.cz> <20230717160227.GA867137@cmpxchg.org> <20230717215105.GA909920@cmpxchg.org> In-Reply-To: <20230717215105.GA909920@cmpxchg.org> From: Nhat Pham Date: Mon, 17 Jul 2023 15:58:45 -0700 Message-ID: Subject: Re: [PATCH] mm: kill frontswap To: Johannes Weiner Cc: Matthew Wilcox , Vlastimil Babka , Andrew Morton , Yosry Ahmed , Christoph Hellwig , Domenico Cerasuolo , konrad.wilk@oracle.com, vitaly.wool@konsulko.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: B714780014 X-Rspam-User: X-Stat-Signature: zp9ax1f7o9bk8d14iht4prgugetoa1zp X-Rspamd-Server: rspam01 X-HE-Tag: 1689634737-478038 X-HE-Meta: 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 xUUK3W32 98H4XDxEGi45LIRnpLj1O3MSjDcY6kWIkC5pei+tHfScaNZ+n3ljRKyEUmYsylM32rnTZuTHH6O+f3BbQ3A95TpjLKSeRNNqd72zhOgqstq4aRWtA640atumcNLiTjnlHov/ysFerWgsXdsgt0Ta8ZpQYC14GdWEdMntM05EQvKI66bn2fjRAS/46uFJcgi+O+2SfndoyjcX8pEf/K7/0URXTGSbVW7PqRr88BPQOB2qJcRU7kvOyHtdcwYpSuhD9QKkHsKEnsS8/otff7Ct1l8rg3ZUWMAXQWZP/9qGTMDpCH9MKHHHAxsgz63y+F7b1+5po97n98RboeGsvxwFkYkmK5NcHtnLd+xuU+HVbep8a6BHoD08e70DENidO3AxUbtqzDiH0mKJzx8O4y7YZLf09yeJmEgBJ4CYE X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jul 17, 2023 at 2:51=E2=80=AFPM Johannes Weiner wrote: > > On Mon, Jul 17, 2023 at 05:07:46PM +0100, Matthew Wilcox wrote: > > On Mon, Jul 17, 2023 at 12:02:27PM -0400, Johannes Weiner wrote: > > > - pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%l= luk %s%s%s%s%s\n", > > > + pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%l= luk %s%s%s%s\n", > > > p->pages<<(PAGE_SHIFT-10), name->name, p->prio, > > > nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), > > > (p->flags & SWP_SOLIDSTATE) ? "SS" : "", > > > (p->flags & SWP_DISCARDABLE) ? "D" : "", > > > (p->flags & SWP_AREA_DISCARD) ? "s" : "", > > > - (p->flags & SWP_PAGE_DISCARD) ? "c" : "", > > > - (frontswap_map) ? "FS" : ""); > > > + (p->flags & SWP_PAGE_DISCARD) ? "c" : ""); > > > > Is it useful information (to the sysadmin) that zswap is enabled? If s= o, > > we might want to print a "Z" instead of a "FS" here (would need to > > know whether enabling zswap succeeded ...) > > I don't think it is needed in this particular place. > > zswap prints to dmesg when it is initialized. And it's easy to runtime > check in sysfs or in /proc/meminfo if it's enabled - that's where I > would look first if I checked a system that's showing zswap issues - > not in the dmesg that may have long wrapped since swapon. +1 I always use /sys/kernel/debug/* and /sys/module/zswap/parameters/* for debugging zswap issues too. > > There is also a warning to dmesg if zswap fails to enable for a given > swapfile. But with the current page allocator implementation this > can't actually fail.