lkml.org 
[lkml]   [2010]   [May]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 1/6] writeback: initial tracing support
    On Tue, 25 May 2010 20:54:07 +1000
    Dave Chinner <david@fromorbit.com> wrote:

    > From: From: Jens Axboe <jens.axboe@oracle.com>
    >
    > Trace queue/sched/exec parts of the writeback loop.

    It would be most useful if this patchset's description provided sample
    tracing output, so we can see what the patch is actually providing us.

    > -#define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info)
    > -
    > -/*
    > - * We don't actually have pdflush, but this one is exported though /proc...
    > - */
    > -int nr_pdflush_threads;
    > -
    > /*
    > * Passed into wb_writeback(), essentially a subset of writeback_control
    > */
    > @@ -63,6 +57,16 @@ struct bdi_work {
    > unsigned long state; /* flag bits, see WS_* */
    > };
    >
    > +#define CREATE_TRACE_POINTS
    > +#include <trace/events/writeback.h>
    > +
    > +#define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info)

    Could/should be implemented in C.

    > +/*
    > + * We don't actually have pdflush, but this one is exported though /proc...
    > + */
    > +int nr_pdflush_threads;

    So this is always zero now?

    We don't want to keep it forever. Add a
    printk_once("nr_pdflush_threads is deprecated") when someone reads it,
    remove it in 2014.

    >
    > ...
    >
    > --- /dev/null
    > +++ b/include/trace/events/writeback.h
    > @@ -0,0 +1,171 @@
    > +#undef TRACE_SYSTEM
    > +#define TRACE_SYSTEM writeback
    > +
    > +#if !defined(_TRACE_WRITEBACK_H) || defined(TRACE_HEADER_MULTI_READ)

    Seems wrong. If you define TRACE_HEADER_MULTI_READ then include this
    header twice, things explode. Which negates the purpose of
    _TRACE_WRITEBACK_H.

    > +#define _TRACE_WRITEBACK_H
    > +
    > +#include <linux/backing-dev.h>
    > +#include <linux/writeback.h>
    > +
    > +TRACE_EVENT(writeback_queue,
    > +
    > + TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_args *args),
    > +
    > + TP_ARGS(bdi, args),
    > +
    > + TP_STRUCT__entry(
    > + __array(char, name, 16)
    > + __field(long, nr_pages)
    > + __field(int, sb)
    > + __field(int, sync_mode)
    > + __field(int, for_kupdate)
    > + __field(int, range_cyclic)
    > + __field(int, for_background)
    > + ),
    > +
    > + TP_fast_assign(
    > + strncpy(__entry->name, dev_name(bdi->dev), 16);
    > + __entry->nr_pages = args->nr_pages;
    > + __entry->sb = !!args->sb;
    > + __entry->for_kupdate = args->for_kupdate;
    > + __entry->range_cyclic = args->range_cyclic;
    > + __entry->for_background = args->for_background;
    > + ),
    > +
    > + TP_printk("%s: pages=%ld, sb=%d, kupdate=%d, range_cyclic=%d "
    > + "for_background=%d", __entry->name, __entry->nr_pages,
    > + __entry->sb, __entry->for_kupdate,
    > + __entry->range_cyclic, __entry->for_background)
    > +);
    > +



    \
     
     \ /
      Last update: 2010-05-27 23:35    [W:0.027 / U:208.432 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site