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Message-ID: <52659b4f2bf3334de824f480fac25c6e028814d2.camel@kernel.org>
Date: Thu, 11 Jul 2024 13:28:48 -0400
From: Jeff Layton <jlayton@...nel.org>
To: "Darrick J. Wong" <djwong@...nel.org>
Cc: Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner
<brauner@...nel.org>, Jan Kara <jack@...e.cz>, Steven Rostedt
<rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, Mathieu
Desnoyers <mathieu.desnoyers@...icios.com>, Chandan Babu R
<chandan.babu@...cle.com>, Theodore Ts'o <tytso@....edu>, Andreas Dilger
<adilger.kernel@...ger.ca>, Chris Mason <clm@...com>, Josef Bacik
<josef@...icpanda.com>, David Sterba <dsterba@...e.com>, Hugh Dickins
<hughd@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>, Jonathan
Corbet <corbet@....net>, Dave Chinner <david@...morbit.com>, Andi Kleen
<ak@...ux.intel.com>, Christoph Hellwig <hch@...radead.org>, Uros Bizjak
<ubizjak@...il.com>, Kent Overstreet <kent.overstreet@...ux.dev>, Arnd
Bergmann <arnd@...db.de>, Randy Dunlap <rdunlap@...radead.org>,
kernel-team@...com, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
linux-xfs@...r.kernel.org, linux-ext4@...r.kernel.org,
linux-btrfs@...r.kernel.org, linux-mm@...ck.org, linux-nfs@...r.kernel.org,
linux-doc@...r.kernel.org
Subject: Re: [PATCH v5 2/9] fs: tracepoints around multigrain timestamp
events
On Thu, 2024-07-11 at 09:49 -0700, Darrick J. Wong wrote:
> On Thu, Jul 11, 2024 at 07:08:06AM -0400, Jeff Layton wrote:
> > Add some tracepoints around various multigrain timestamp events.
> >
> > Signed-off-by: Jeff Layton <jlayton@...nel.org>
> > ---
> > fs/inode.c | 5 ++
> > fs/stat.c | 3 ++
> > include/trace/events/timestamp.h | 109
> > +++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 117 insertions(+)
> >
> > diff --git a/fs/inode.c b/fs/inode.c
> > index 2b5889ff7b36..81b45e0a95a6 100644
> > --- a/fs/inode.c
> > +++ b/fs/inode.c
> > @@ -22,6 +22,9 @@
> > #include <linux/iversion.h>
> > #include <linux/rw_hint.h>
> > #include <trace/events/writeback.h>
> > +#define CREATE_TRACE_POINTS
> > +#include <trace/events/timestamp.h>
> > +
> > #include "internal.h"
> >
> > /*
> > @@ -2571,6 +2574,7 @@ struct timespec64
> > inode_set_ctime_to_ts(struct inode *inode, struct timespec64 t
> > {
> > inode->i_ctime_sec = ts.tv_sec;
> > inode->i_ctime_nsec = ts.tv_nsec & ~I_CTIME_QUERIED;
> > + trace_inode_set_ctime_to_ts(inode, &ts);
> > return ts;
> > }
> > EXPORT_SYMBOL(inode_set_ctime_to_ts);
> > @@ -2670,6 +2674,7 @@ struct timespec64
> > inode_set_ctime_current(struct inode *inode)
> > if (try_cmpxchg(&inode->i_ctime_nsec, &cur,
> > now_ts.tv_nsec)) {
> > /* If swap occurred, then we're (mostly) done */
> > inode->i_ctime_sec = now_ts.tv_sec;
> > + trace_ctime_ns_xchg(inode, cns, now_ts.tv_nsec,
> > cur);
> > } else {
> > /*
> > * Was the change due to someone marking the old
> > ctime QUERIED?
> > diff --git a/fs/stat.c b/fs/stat.c
> > index df7fdd3afed9..552dfd67688b 100644
> > --- a/fs/stat.c
> > +++ b/fs/stat.c
> > @@ -23,6 +23,8 @@
> > #include <linux/uaccess.h>
> > #include <asm/unistd.h>
> >
> > +#include <trace/events/timestamp.h>
> > +
> > #include "internal.h"
> > #include "mount.h"
> >
> > @@ -49,6 +51,7 @@ void fill_mg_cmtime(struct kstat *stat, u32
> > request_mask, struct inode *inode)
> > stat->mtime = inode_get_mtime(inode);
> > stat->ctime.tv_sec = inode->i_ctime_sec;
> > stat->ctime.tv_nsec =
> > ((u32)atomic_fetch_or(I_CTIME_QUERIED, pcn)) & ~I_CTIME_QUERIED;
> > + trace_fill_mg_cmtime(inode, &stat->ctime, &stat->mtime);
> > }
> > EXPORT_SYMBOL(fill_mg_cmtime);
> >
> > diff --git a/include/trace/events/timestamp.h
> > b/include/trace/events/timestamp.h
> > new file mode 100644
> > index 000000000000..3a603190b46c
> > --- /dev/null
> > +++ b/include/trace/events/timestamp.h
> > @@ -0,0 +1,109 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#undef TRACE_SYSTEM
> > +#define TRACE_SYSTEM timestamp
> > +
> > +#if !defined(_TRACE_TIMESTAMP_H) ||
> > defined(TRACE_HEADER_MULTI_READ)
> > +#define _TRACE_TIMESTAMP_H
> > +
> > +#include <linux/tracepoint.h>
> > +#include <linux/fs.h>
> > +
> > +TRACE_EVENT(inode_set_ctime_to_ts,
> > + TP_PROTO(struct inode *inode,
> > + struct timespec64 *ctime),
> > +
> > + TP_ARGS(inode, ctime),
> > +
> > + TP_STRUCT__entry(
> > + __field(dev_t, dev)
> > + __field(ino_t, ino)
> > + __field(time64_t, ctime_s)
> > + __field(u32, ctime_ns)
> > + __field(u32, gen)
> > + ),
> > +
> > + TP_fast_assign(
> > + __entry->dev = inode->i_sb->s_dev;
>
> Odd indenting of the second columns between the struct definition
> above
> and the assignment code here.
>
> > + __entry->ino = inode->i_ino;
> > + __entry->gen = inode->i_generation;
> > + __entry->ctime_s = ctime->tv_sec;
> > + __entry->ctime_ns = ctime->tv_nsec;
> > + ),
> > +
> > + TP_printk("ino=%d:%d:%ld:%u ctime=%lld.%u",
> > + MAJOR(__entry->dev), MINOR(__entry->dev), __entry-
> > >ino, __entry->gen,
> > + __entry->ctime_s, __entry->ctime_ns
> > + )
> > +);
> > +
> > +TRACE_EVENT(ctime_ns_xchg,
> > + TP_PROTO(struct inode *inode,
> > + u32 old,
> > + u32 new,
> > + u32 cur),
> > +
> > + TP_ARGS(inode, old, new, cur),
> > +
> > + TP_STRUCT__entry(
> > + __field(dev_t, dev)
> > + __field(ino_t, ino)
> > + __field(u32, gen)
> > + __field(u32, old)
> > + __field(u32, new)
> > + __field(u32, cur)
> > + ),
> > +
> > + TP_fast_assign(
> > + __entry->dev = inode->i_sb->s_dev;
> > + __entry->ino = inode->i_ino;
> > + __entry->gen = inode->i_generation;
> > + __entry->old = old;
> > + __entry->new = new;
> > + __entry->cur = cur;
> > + ),
> > +
> > + TP_printk("ino=%d:%d:%ld:%u old=%u:%c new=%u cur=%u:%c",
> > + MAJOR(__entry->dev), MINOR(__entry->dev), __entry-
> > >ino, __entry->gen,
> > + __entry->old & ~I_CTIME_QUERIED, __entry->old &
> > I_CTIME_QUERIED ? 'Q' : '-',
> > + __entry->new,
> > + __entry->cur & ~I_CTIME_QUERIED, __entry->cur &
> > I_CTIME_QUERIED ? 'Q' : '-'
>
> This /might/ be overkill for a single flag, but anything you put in
> the
> TP_printk seems to end up in the format file:
>
> # cat
> /sys/kernel/debug/tracing/events/xfs/xfbtree_create_root_buf/format
> name: xfbtree_create_root_buf
> ID: 1644
> format:
> field:unsigned short common_type; offset:0;
> size:2; signed:0;
> field:unsigned char common_flags; offset:2;
> size:1; signed:0;
> field:unsigned char common_preempt_count;
> offset:3; size:1; signed:0;
> field:int common_pid; offset:4; size:4; signed:1;
>
> field:unsigned long xfino; offset:8; size:8;
> signed:0;
> field:xfs_daddr_t bno; offset:16; size:8; signed:1;
> field:int nblks; offset:24; size:4; signed:1;
> field:int hold; offset:28; size:4; signed:1;
> field:int pincount; offset:32; size:4; signed:1;
> field:unsigned int lockval; offset:36; size:4;
> signed:0;
> field:unsigned int flags; offset:40; size:4;
> signed:0;
>
> print fmt: "xfino 0x%lx daddr 0x%llx bbcount 0x%x hold %d pincount %d
> lock %d flags %s", REC->xfino, (unsigned long long)REC->bno, REC-
> >nblks, REC->hold, REC->pincount, REC->lockval, __print_flags(REC-
> >flags, "|", { (1u << 0), "READ" }, { (1u << 1), "WRITE" }, { (1u <<
> 2), "READ_AHEAD" }, { (1u << 3), "NO_IOACCT" }, { (1u << 4), "ASYNC"
> }, { (1u << 5), "DONE" }, { (1u << 6), "STALE" }, { (1u << 7),
> "WRITE_FAIL" }, { (1u << 16), "INODES" }, { (1u << 17), "DQUOTS" }, {
> (1u << 18), "LOG_RECOVERY" }, { (1u << 20), "PAGES" }, { (1u << 21),
> "KMEM" }, { (1u << 22), "DELWRI_Q" }, { (1u << 28), "LIVESCAN" }, {
> (1u << 29), "INCORE" }, { (1u << 30), "TRYLOCK" }, { (1u << 31),
> "UNMAPPED" })
>
> I /think/ all that code gets compiled (interpreted?) as if it were C
> code, but a more compact format might be:
>
> #define CTIME_QUERIED_FLAGS \
> { I_CTIME_QUERIED, "queried" }
>
> TP_printk("ino=%d:%d:%ld:%u old=%u:%s new=%u cur=%u:%c",
> MAJOR(__entry->dev), MINOR(__entry->dev), __entry-
> >ino, __entry->gen,
> __entry->old & ~I_CTIME_QUERIED,
> __print_flags(__entry->old & I_CTIME_QUERIED, "|",
> CTIME_QUERIED_FLAGS),
> ...
>
> But, again, that could be overkill for a single flag. Aside from my
> minor bikeshedding, this all looks good, and I like that we can now
> monitor what's going on wrt ctime. :)
>
That seems reasonable. I hadn't looked at the unrolled format
monstrosity, but making it more compact is good. I'll make that change
and see how it looks.
Thanks for the reviews so far!
> > + )
> > +);
> > +
> > +TRACE_EVENT(fill_mg_cmtime,
> > + TP_PROTO(struct inode *inode,
> > + struct timespec64 *ctime,
> > + struct timespec64 *mtime),
> > +
> > + TP_ARGS(inode, ctime, mtime),
> > +
> > + TP_STRUCT__entry(
> > + __field(dev_t, dev)
> > + __field(ino_t, ino)
> > + __field(time64_t, ctime_s)
> > + __field(time64_t, mtime_s)
> > + __field(u32, ctime_ns)
> > + __field(u32, mtime_ns)
> > + __field(u32, gen)
> > + ),
> > +
> > + TP_fast_assign(
> > + __entry->dev = inode->i_sb->s_dev;
> > + __entry->ino = inode->i_ino;
> > + __entry->gen = inode->i_generation;
> > + __entry->ctime_s = ctime->tv_sec;
> > + __entry->mtime_s = mtime->tv_sec;
> > + __entry->ctime_ns = ctime->tv_nsec;
> > + __entry->mtime_ns = mtime->tv_nsec;
> > + ),
> > +
> > + TP_printk("ino=%d:%d:%ld:%u ctime=%lld.%u mtime=%lld.%u",
> > + MAJOR(__entry->dev), MINOR(__entry->dev), __entry-
> > >ino, __entry->gen,
> > + __entry->ctime_s, __entry->ctime_ns,
> > + __entry->mtime_s, __entry->mtime_ns
> > + )
> > +);
> > +#endif /* _TRACE_TIMESTAMP_H */
> > +
> > +/* This part must be outside protection */
> > +#include <trace/define_trace.h>
> >
> > --
> > 2.45.2
> >
> >
--
Jeff Layton <jlayton@...nel.org>
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