[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH v2 13/20] xen/events: fifo: Make it running on 64KB granularity

Hi Stefano,

On 16/07/2015 16:43, Stefano Stabellini wrote:
On Thu, 9 Jul 2015, Julien Grall wrote:
Only use the first 4KB of the page to store the events channel info. It
means that we will wast 60KB every time we allocate page for:
                       ^ waste

      * control block: a page is allocating per CPU
      * event array: a page is allocating everytime we need to expand it

I think we can reduce the memory waste for the 2 areas by:

     * control block: sharing between multiple vCPUs. Although it will
     require some bookkeeping in order to not free the page when the CPU
     goes offline and the other CPUs sharing the page still there

     * event array: always extend the array event by 64K (i.e 16 4K
     chunk). That would require more care when we fail to expand the
     event channel.

But this is not implemented in this series, right?

Yes, it's some ideas to improve the code.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: David Vrabel <david.vrabel@xxxxxxxxxx>
  drivers/xen/events/events_base.c | 2 +-
  drivers/xen/events/events_fifo.c | 2 +-
  2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 96093ae..858d2f6 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -40,11 +40,11 @@
  #include <asm/idle.h>
  #include <asm/io_apic.h>
  #include <asm/xen/pci.h>
-#include <xen/page.h>
  #include <asm/sync_bitops.h>
  #include <asm/xen/hypercall.h>
  #include <asm/xen/hypervisor.h>
+#include <xen/page.h>

  #include <xen/xen.h>
  #include <xen/hvm.h>

Spurious change?

No, xen/page.h was only included for x86 before. Now, it's included for every architecture.

This is required in order to get XEN_PAGE_SIZE.


Julien Grall

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.