lkml.org 
[lkml]   [2021]   [Feb]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [PATCH v23 10/15] mm/damon/dbgfs: Support multiple contexts
    Date
    On Tue, 15 Dec 2020 12:54:43 +0100 SeongJae Park <sjpark@amazon.com> wrote:

    > From: SeongJae Park <sjpark@amazon.de>
    >
    > In some use cases, users would want to run multiple monitoring context.
    > For example, if a user wants a high precision monitoring and dedicating
    > multiple CPUs for the job is ok, because DAMON creates one monitoring
    > thread per one context, the user can split the monitoring target regions
    > into multiple small regions and create one context for each region. Or,
    > someone might want to simultaneously monitor different address spaces,
    > e.g., both virtual address space and physical address space.
    >
    > The DAMON's API allows such usage, but 'damon-dbgfs' does not.
    > Therefore, only kernel space DAMON users can do multiple contexts
    > monitoring.
    >
    > This commit allows the user space DAMON users to use multiple contexts
    > monitoring by introducing two new 'damon-dbgfs' debugfs files,
    > 'mk_context' and 'rm_context'. Users can create a new monitoring
    > context by writing the desired name of the new context to 'mk_context'.
    > Then, a new directory with the name and having the files for setting of
    > the context ('attrs', 'target_ids' and 'record') will be created under
    > the debugfs directory. Writing the name of the context to remove to
    > 'rm_context' will remove the related context and directory.
    >
    > Signed-off-by: SeongJae Park <sjpark@amazon.de>
    > ---
    > mm/damon/dbgfs.c | 213 ++++++++++++++++++++++++++++++++++++++++++++++-
    > 1 file changed, 211 insertions(+), 2 deletions(-)
    >
    > diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
    > index a1512d3e5afe..46186b057e1a 100644
    > --- a/mm/damon/dbgfs.c
    > +++ b/mm/damon/dbgfs.c
    [...]
    > +/*
    > + * Remove a context of @name and its debugfs directory.
    > + *
    > + * This function should be called while holding damon_dbgfs_lock.
    > + *
    > + * Return 0 on success, negative error code otherwise.
    > + */
    > +static int dbgfs_rm_context(char *name)
    > +{
    > + struct dentry *root, *dir, **new_dirs;
    > + struct damon_ctx **new_ctxs;
    > + int i, j;
    > +
    > + if (damon_nr_running_ctxs())
    > + return -EBUSY;
    > +
    > + root = dbgfs_dirs[0];
    > + if (!root)
    > + return -ENOENT;
    > +
    > + dir = debugfs_lookup(name, root);
    > + if (!dir)
    > + return -ENOENT;
    > +
    > + new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs),
    > + GFP_KERNEL);
    > + if (!new_dirs)
    > + return -ENOMEM;
    > +
    > + new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs),
    > + GFP_KERNEL);
    > + if (!new_ctxs) {
    > + kfree(new_dirs);
    > + return -ENOMEM;
    > + }
    > +
    > + for (i = 0, j = 0; i < dbgfs_nr_ctxs; i++) {
    > + if (dbgfs_dirs[i] == dir) {
    > + debugfs_remove(dbgfs_dirs[i]);
    > + dbgfs_destroy_ctx(dbgfs_ctxs[i]);

    In case of virtual address monitoring, dbgfs_destroy_ctx() calls
    damon_destroy_ctx() and damon_destroy_ctx() doesn't put the target pids. I
    will fix this in the next version.

    > + continue;
    > + }
    > + new_dirs[j] = dbgfs_dirs[i];
    > + new_ctxs[j++] = dbgfs_ctxs[i];
    > + }
    > +
    > + kfree(dbgfs_dirs);
    > + kfree(dbgfs_ctxs);
    > +
    > + dbgfs_dirs = new_dirs;
    > + dbgfs_ctxs = new_ctxs;
    > + dbgfs_nr_ctxs--;
    > +
    > + return 0;
    > +}

    Thanks,
    SeongJae Park
    [...]

    \
     
     \ /
      Last update: 2021-02-02 13:30    [W:8.259 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site