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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id bk42-20020a05620a1a2a00b006fa16fe93bbsm2936402qkb.15.2023.02.03.16.15.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Feb 2023 16:15:21 -0800 (PST) Date: Fri, 3 Feb 2023 16:15:12 -0800 (PST) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Trond Myklebust cc: Hugh Dickins , Charles Edward Lever , Benjamin Coddington , Linux NFS Mailing List , Anna Schumaker , Alexander Viro , Amir Goldstein , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: git regression failures with v6.2-rc NFS client In-Reply-To: <0D7A0393-EE80-4785-9A83-44CF8269758B@hammerspace.com> Message-ID: References: <9A4A5673-691D-47EC-BC44-C43BE7E50A48@oracle.com> <5FF4061F-108C-4555-A32D-DDBFA80EE4E7@redhat.com> <44CB1E86-60E0-4CF0-9FD4-BB7E446542B7@redhat.com> <1AAC6854-2591-4B21-952A-BC58180B4091@oracle.com> <41813D21-95C8-44E3-BB97-1E9C03CE7FE5@redhat.com> <79261B77-35D0-4E36-AA29-C7BF9FB734CC@oracle.com> <104B6879-5223-485F-B099-767F741EB15B@redhat.com> <966AEC32-A7C9-4B97-A4F7-098AF6EF0067@oracle.com> <545B5AB7-93A6-496E-924E-AE882BF57B72@hammerspace.com> <4dd32d-9ea3-4330-454a-36f1189d599@google.com> <0D7A0393-EE80-4785-9A83-44CF8269758B@hammerspace.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="-1463760895-1720490057-1675469721=:2591" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: E97351A0003 X-Stat-Signature: jxjdp85rn6fjikffypwmzmuzdd8zzoyo X-Rspam-User: X-HE-Tag: 1675469722-733696 X-HE-Meta: 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 n+raaFhX 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 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: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1463760895-1720490057-1675469721=:2591 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE On Sat, 4 Feb 2023, Trond Myklebust wrote: > > On Feb 3, 2023, at 18:53, Hugh Dickins wrote: > > On Fri, 3 Feb 2023, Chuck Lever III wrote: > >>> On Feb 3, 2023, at 5:26 PM, Trond Myklebust = wrote: > >>> The bottom line is that you=E2=80=99ve always been playing the lotter= y when mounting tmpfs over NFS. > >>=20 > >> I'm not debating the truth of that. I just don't think we should > >> be making that situation needlessly worse. > >>=20 > >> And I would be much more comfortable with this if it appeared in > >> a man page or on our wiki, or ... I'm sorry, but "some email in > >> 2001" is not documentation a user should be expected to find. > >=20 > > I very much agree with you, Chuck. Making something imperfect > > significantly worse is called "a regression". > >=20 > > And I would expect the (laudable) optimization which introduced > > that regression to be reverted from 6.2 for now, unless (I imagine > > not, but have no clue) it can be easily conditionalized somehow on > > not-tmpfs or not-simple_dir_operations. But that's not my call. > >=20 > > What is the likelihood that simple_dir_operations will be enhanced, > > or a satisfactory complicated_dir_operations added? I can assure > > you, never by me! If Al or Amir or some dcache-savvy FS folk have > > time on their hands and an urge to add what's wanted, great: but > > that surely will not come in 6.2, if ever. > >=20 > > More likely that effort would have to come from the NFS(D) end, > > who will see the benefit. And if there's some little tweak to be > > made to simple_dir_operations, which will give you the hint you need > > to handle it better, I expect fsdevel would welcome a patch or two. > >=20 > > Hugh >=20 >=20 > No! If it was impossible to hit this problem before the patch, then I mig= ht agree with you. However what it does is exposes a problem that has alway= s existed, but was a lot less likely to happen timing wise when we were all= owing glibc to suck in all 50000 or so directory entries in one gulp. >=20 > IOW: this patch doesn=E2=80=99t cause the problem, it just makes it easie= r to hit when you are using a high performance setup like Chuck's. It was a= lways easy to hit when you were using slower networking and/or smaller rsiz= e values against a remote server with multiple clients creating + deleting = files in the same NFS exported tmpfs directory. > _________________________________ > Trond Myklebust > Linux NFS client maintainer, Hammerspace > trond.myklebust@hammerspace.com I can only repeat, making something imperfect significantly worse is called "a regression". Hugh ---1463760895-1720490057-1675469721=:2591--