From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 471B6182B4; Tue, 4 Feb 2025 14:53:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738680796; cv=none; b=N0F3emFMaOUfRt9CWBeYUcdQjmKg1X6l2ZQKS3/YOYyqDY8SLtE8dckL0bSUuoWpEz6JnImh8oxKc+f+AUY6+bOyc9T/5Mt3wogE3YXNPfaZuIEZ4RUhk0BlSoENAcyS7DH6q6Egz/EfFclqzWocpAozgv0YK9eVGu7rMSDKQPE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738680796; c=relaxed/simple; bh=cS+KYmTiDZbvQ/qAiqt3v7VU67F5RKNkSobPiQTuc20=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=QnYmWGrRwUSXagyrt5eoUpDexoja2Kyfp10SwtfZCtwQTZ8phCIien6+JLGvXpQdt2iV6cLBTUUo8PkFAiU37UI9Gq3RzjS1eecj86XWjSNZcSc/kXJz+wxgazRH4YMKoXlkAUjWcJR52pz/MUPNESfVDNJb89iNBPQZqrsVo4I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XxqXBcOp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XxqXBcOp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 82C2EC4CEDF; Tue, 4 Feb 2025 14:53:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738680795; bh=cS+KYmTiDZbvQ/qAiqt3v7VU67F5RKNkSobPiQTuc20=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=XxqXBcOpNlD5G+7XbC1+c+VcasdfeyjKlXtF4JkSu+4hwyFOzpMK9zaSF9p7/avJr 7DnGyblqKnI8RUm5QvWKoDhXMSMwJHcPRGlQuR4jsq0DhRffzkZ21b1oa36i3Rv72f a9daKNmZTDTgZjJxv5+NoANKDMCADlhnat9cDfgN6Nlkfz/xEay4R5zT41SWuWWrLU /KOxZLuMPpe+jnDfjrbDJcG6BDxO4wS58FjPTfF/r+MvEtzdhRG2YDx5deizIEQj6B eulkktWJbHrJI6/YbrV6UUSAJAgxhZp1+vkekRgdtFqhBOa86XWqhjzjpVRqyUUOq9 7CGnfgVk76bXA== Message-ID: <10981ed475d3b7d2d0bef73ea6286bc60aa484b2.camel@kernel.org> Subject: Re: [PATCH] pipe: don't update {a,c,m}time for anonymous pipes From: Jeff Layton To: Oleg Nesterov , Christian Brauner , Linus Torvalds Cc: David Howells , "Gautham R. Shenoy" , K Prateek Nayak , Mateusz Guzik , Neeraj Upadhyay , Oliver Sang , Swapnil Sapkal , WangYuli , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 04 Feb 2025 09:53:13 -0500 In-Reply-To: <20250204132153.GA20921@redhat.com> References: <20250204132153.GA20921@redhat.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn VluJH0/RcxEeFbnSaswVChNSGa7mXJrTR22lRL6ZPjdMgS2Km90haWPRc8Wolcz07Y2se0xpGVLEQ cDEsvv5IMmeMe1/qLZ6NaVkNuL3WOXvxaVT9USW1+/SGipO2IpKJjeDZfehlB/kpfF24+RrK+seQf 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Yy9YbXtWctUz8uvDR7shsQxAhX3qO7DilMtuGo1v97I/Kx4gXQ52syh/w6EBny71CZrOgD6kJwPVV AaM1LRC28muq91WCFhs/nzHozpbzcheyGtMUI2Ao4K6mnY+3zIuXPygZMFr9KXE6fF7HzKxKuZMJO aEZCiDOq0anx6FmOzs5E6Jqdpo/mtI8beK+BE7Va6ni7YrQlnT0i3vaTVMTiCThbqsB20VrbMjlhp f8lfK1XVNbRq/R7GZ9zHESlsa35ha60yd/j3pu5hT2xyy8krV8vGhHvnJ1XRMJBAB/UYb6FyC7S+m QZIQXVeAA+smfTT0tDrisj1U5x6ZB9b3nBg65kc= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2025-02-04 at 14:21 +0100, Oleg Nesterov wrote: > These numbers are visible in fstat() but hopefully nobody uses this > information and file_accessed/file_update_time are not that cheap. > Stupid test-case: >=20 > #include > #include > #include > #include > #include > #include >=20 > static char buf[17 * 4096]; > static struct timeval TW, TR; >=20 > int wr(int fd, int size) > { > int c, r; > struct timeval t0, t1; >=20 > gettimeofday(&t0, NULL); > for (c =3D 0; (r =3D write(fd, buf, size)) > 0; c +=3D r); > gettimeofday(&t1, NULL); > timeradd(&TW, &t1, &TW); > timersub(&TW, &t0, &TW); >=20 > return c; > } >=20 > int rd(int fd, int size) > { > int c, r; > struct timeval t0, t1; >=20 > gettimeofday(&t0, NULL); > for (c =3D 0; (r =3D read(fd, buf, size)) > 0; c +=3D r); > gettimeofday(&t1, NULL); > timeradd(&TR, &t1, &TR); > timersub(&TR, &t0, &TR); >=20 > return c; > } >=20 > int main(int argc, const char *argv[]) > { > int fd[2], nb =3D 1, loop, size; >=20 > assert(argc =3D=3D 3); > loop =3D atoi(argv[1]); > size =3D atoi(argv[2]); >=20 > assert(pipe(fd) =3D=3D 0); > assert(ioctl(fd[0], FIONBIO, &nb) =3D=3D 0); > assert(ioctl(fd[1], FIONBIO, &nb) =3D=3D 0); >=20 > assert(size <=3D sizeof(buf)); > while (loop--) > assert(wr(fd[1], size) =3D=3D rd(fd[0], size)); >=20 > struct timeval tt; > timeradd(&TW, &TR, &tt); > printf("TW =3D %lu.%03lu TR =3D %lu.%03lu TT =3D %lu.%03lu\n", > TW.tv_sec, TW.tv_usec/1000, > TR.tv_sec, TR.tv_usec/1000, > tt.tv_sec, tt.tv_usec/1000); >=20 > return 0; > } >=20 > Before: > # for i in 1 2 3; do /host/tmp/test 10000 100; done > TW =3D 8.047 TR =3D 5.845 TT =3D 13.893 > TW =3D 8.091 TR =3D 5.872 TT =3D 13.963 > TW =3D 8.083 TR =3D 5.885 TT =3D 13.969 > After: > # for i in 1 2 3; do /host/tmp/test 10000 100; done > TW =3D 4.752 TR =3D 4.664 TT =3D 9.416 > TW =3D 4.684 TR =3D 4.608 TT =3D 9.293 > TW =3D 4.736 TR =3D 4.652 TT =3D 9.388 >=20 > Signed-off-by: Oleg Nesterov > --- > fs/pipe.c | 21 ++++++++++++++------- > 1 file changed, 14 insertions(+), 7 deletions(-) >=20 > diff --git a/fs/pipe.c b/fs/pipe.c > index 94b59045ab44..baaa8c0817f1 100644 > --- a/fs/pipe.c > +++ b/fs/pipe.c > @@ -247,6 +247,11 @@ static inline unsigned int pipe_update_tail(struct p= ipe_inode_info *pipe, > return tail; > } > =20 > +static inline bool is_pipe_inode(struct inode *inode) > +{ > + return inode->i_sb->s_magic =3D=3D PIPEFS_MAGIC; > +} > + > static ssize_t > pipe_read(struct kiocb *iocb, struct iov_iter *to) > { > @@ -404,7 +409,7 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) > if (wake_next_reader) > wake_up_interruptible_sync_poll(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM)= ; > kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); > - if (ret > 0) > + if (ret > 0 && !is_pipe_inode(file_inode(filp))) > file_accessed(filp); > return ret; > } > @@ -604,11 +609,13 @@ pipe_write(struct kiocb *iocb, struct iov_iter *fro= m) > kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); > if (wake_next_writer) > wake_up_interruptible_sync_poll(&pipe->wr_wait, EPOLLOUT | EPOLLWRNORM= ); > - if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) { > - int err =3D file_update_time(filp); > - if (err) > - ret =3D err; > - sb_end_write(file_inode(filp)->i_sb); > + if (ret > 0 && !is_pipe_inode(file_inode(filp))) { > + if (sb_start_write_trylock(file_inode(filp)->i_sb)) { > + int err =3D file_update_time(filp); > + if (err) > + ret =3D err; > + sb_end_write(file_inode(filp)->i_sb); > + } > } > return ret; > } > @@ -1108,7 +1115,7 @@ static void wake_up_partner(struct pipe_inode_info = *pipe) > static int fifo_open(struct inode *inode, struct file *filp) > { > struct pipe_inode_info *pipe; > - bool is_pipe =3D inode->i_sb->s_magic =3D=3D PIPEFS_MAGIC; > + bool is_pipe =3D is_pipe_inode(inode); > int ret; > =20 > filp->f_pipe =3D 0; Oh _anonymous_ pipes. You can disregard my earlier questions: Reviewed-by: Jeff Layton