From nobody Sun Aug 21 16:05:15 2022 X-Original-To: freebsd-fs@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4M9gLx5KSQz4Z8ZR for ; Sun, 21 Aug 2022 16:05:29 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4M9gLw3lJjz3DNf for ; Sun, 21 Aug 2022 16:05:28 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.16.1/8.16.1) with ESMTPS id 27LG5FZ1064846 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Sun, 21 Aug 2022 19:05:18 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by tom.home (8.16.1/8.16.1/Submit) id 27LG5FpN064823; Sun, 21 Aug 2022 19:05:15 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Sun, 21 Aug 2022 19:05:15 +0300 From: Konstantin Belousov To: Rick Macklem Cc: FreeBSD Filesystems Subject: Re: SEEK_DATA/SEEK_HOLE with vnode locked Message-ID: References: List-Id: Filesystems List-Archive: https://lists.freebsd.org/archives/freebsd-fs List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-fs@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FORGED_GMAIL_RCVD,FREEMAIL_FROM, NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on tom.home X-Rspamd-Queue-Id: 4M9gLw3lJjz3DNf X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=gmail.com (policy=none); spf=softfail (mx1.freebsd.org: 2001:470:d5e7:1::1 is neither permitted nor denied by domain of kostikbel@gmail.com) smtp.mailfrom=kostikbel@gmail.com X-Spamd-Result: default: False [-1.85 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.99)[-0.992]; NEURAL_SPAM_MEDIUM(0.14)[0.140]; MIME_GOOD(-0.10)[text/plain]; DMARC_POLICY_SOFTFAIL(0.10)[gmail.com : No valid SPF, No valid DKIM,none]; RCPT_COUNT_TWO(0.00)[2]; MLMMJ_DEST(0.00)[freebsd-fs@freebsd.org]; ASN(0.00)[asn:6939, ipnet:2001:470::/32, country:US]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; RCVD_TLS_LAST(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_DN_ALL(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; FREEMAIL_FROM(0.00)[gmail.com]; FROM_HAS_DN(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; HAS_XAW(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; R_SPF_SOFTFAIL(0.00)[~all:c]; ARC_NA(0.00)[] X-ThisMailContainsUnwantedMimeParts: N On Sun, Aug 21, 2022 at 12:02:48AM +0000, Rick Macklem wrote: > Just to summarize this... > I was able to do a VOP_SEEK() which would be called with a > LK_SHARED locked vnode and it seemed to work fine. > > However, ReadPlus (which is like Read, but allows for > holes to be represented as in the reply > instead of a stream of 0 bytes) seems to be a performance > dud. > > I was surprised how poorly it performed compares to ordinary > Read. Typically it would take 60% longer to read a file. I tried > sparse and non-sparse files of various sizes and they always > took longer. (If I disabled SEEK_DATA/SEEK_HOLE in the server > code, so it never actually did holes, it worked comparably to > regular Read, so somehow the overhead of doing SEEK_DATA/SEEK_HOLE > was a big performance hit. It was using LK_SHARED locks, so > it wasn't serializing the reads, but I don't really know why it > performed so poorly?) What filesystem did you used on server? > > Anyhow, unless the performance issue gets resolved, there is > no reason to commit the code to FreeBSD's main. > (NFSv4.2 operations, like ReadPlus, are all optional and are not > required for an RFC conformant implementation.) Why not commit? It might make sense to add it, but guard under some knob.