Re: [PATCH v5 06/12] tests/plugin/mem: migrate to new per_vcpu API

[Luc Michel <luc.michel@amd.com>]

On 14:56 Tue 27 Feb     , Pierrick Bouvier wrote:
> Hi Luc,
> 
> On 2/27/24 1:35 PM, Luc Michel wrote:
> > Hi Pierrick,
> > 
> > On 13:14 Mon 26 Feb     , Pierrick Bouvier wrote:
> > > Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
> > > ---
> > >   tests/plugin/mem.c | 40 +++++++++++++++++++++++++---------------
> > >   1 file changed, 25 insertions(+), 15 deletions(-)
> > > 
> > > diff --git a/tests/plugin/mem.c b/tests/plugin/mem.c
> > > index 44e91065ba7..d4729f5e015 100644
> > > --- a/tests/plugin/mem.c
> > > +++ b/tests/plugin/mem.c
> > > @@ -16,9 +16,14 @@
> > > 
> > >   QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
> > > 
> > > -static uint64_t inline_mem_count;
> > > -static uint64_t cb_mem_count;
> > > -static uint64_t io_count;
> > > +typedef struct {
> > > +    uint64_t mem_count;
> > > +    uint64_t io_count;
> > > +} CPUCount;
> > > +
> > > +static struct qemu_plugin_scoreboard *counts;
> > > +static qemu_plugin_u64 mem_count;
> > > +static qemu_plugin_u64 io_count;
> > 
> > I see that you merged inline and callback counts into the same variable.
> > 
> > I wonder... For this test don't you want to keep a plain uint64_t for
> > callback counts? I have the feeling that this test was made so one can
> > make sure inline and callback counts match.
> > 
> 
> Indeed, the new API guarantees thread safety (current inline
> implementation was racy), so this plugin now gives the exact same result
> whether you use inline ops or callbacks. In more, callback based
> approach can be implemented without any lock, as we are counting per
> vcpu. Thus, it's faster and safer.
> 
> Regarding the "testing" side, this series introduce a new plugin
> tests/plugin/inline.c that allows to test all thoses cases in a single
> plugin. Thus, it's not needed that other plugins offer a way to test this.

I see! Then:

Reviewed-by: Luc Michel <luc.michel@amd.com>

> 
> Thanks for your review.
> 
> > Luc
> > 
> > >   static bool do_inline, do_callback;
> > >   static bool do_haddr;
> > >   static enum qemu_plugin_mem_rw rw = QEMU_PLUGIN_MEM_RW;
> > > @@ -27,16 +32,16 @@ static void plugin_exit(qemu_plugin_id_t id, void *p)
> > >   {
> > >       g_autoptr(GString) out = g_string_new("");
> > > 
> > > -    if (do_inline) {
> > > -        g_string_printf(out, "inline mem accesses: %" PRIu64 "\n", inline_mem_count);
> > > -    }
> > > -    if (do_callback) {
> > > -        g_string_append_printf(out, "callback mem accesses: %" PRIu64 "\n", cb_mem_count);
> > > +    if (do_inline || do_callback) {
> > > +        g_string_printf(out, "mem accesses: %" PRIu64 "\n",
> > > +                        qemu_plugin_u64_sum(mem_count));
> > >       }
> > >       if (do_haddr) {
> > > -        g_string_append_printf(out, "io accesses: %" PRIu64 "\n", io_count);
> > > +        g_string_append_printf(out, "io accesses: %" PRIu64 "\n",
> > > +                               qemu_plugin_u64_sum(io_count));
> > >       }
> > >       qemu_plugin_outs(out->str);
> > > +    qemu_plugin_scoreboard_free(counts);
> > >   }
> > > 
> > >   static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t meminfo,
> > > @@ -46,12 +51,12 @@ static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t meminfo,
> > >           struct qemu_plugin_hwaddr *hwaddr;
> > >           hwaddr = qemu_plugin_get_hwaddr(meminfo, vaddr);
> > >           if (qemu_plugin_hwaddr_is_io(hwaddr)) {
> > > -            io_count++;
> > > +            qemu_plugin_u64_add(io_count, cpu_index, 1);
> > >           } else {
> > > -            cb_mem_count++;
> > > +            qemu_plugin_u64_add(mem_count, cpu_index, 1);
> > >           }
> > >       } else {
> > > -        cb_mem_count++;
> > > +        qemu_plugin_u64_add(mem_count, cpu_index, 1);
> > >       }
> > >   }
> > > 
> > > @@ -64,9 +69,10 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
> > >           struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, i);
> > > 
> > >           if (do_inline) {
> > > -            qemu_plugin_register_vcpu_mem_inline(insn, rw,
> > > -                                                 QEMU_PLUGIN_INLINE_ADD_U64,
> > > -                                                 &inline_mem_count, 1);
> > > +            qemu_plugin_register_vcpu_mem_inline_per_vcpu(
> > > +                insn, rw,
> > > +                QEMU_PLUGIN_INLINE_ADD_U64,
> > > +                mem_count, 1);
> > >           }
> > >           if (do_callback) {
> > >               qemu_plugin_register_vcpu_mem_cb(insn, vcpu_mem,
> > > @@ -117,6 +123,10 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
> > >           }
> > >       }
> > > 
> > > +    counts = qemu_plugin_scoreboard_new(sizeof(CPUCount));
> > > +    mem_count = qemu_plugin_scoreboard_u64_in_struct(
> > > +        counts, CPUCount, mem_count);
> > > +    io_count = qemu_plugin_scoreboard_u64_in_struct(counts, CPUCount, io_count);
> > >       qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
> > >       qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
> > >       return 0;
> > > --
> > > 2.43.0
> > > 
> > > 
> > 

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