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Re: [PATCH V3 17/23] xen/ioreq: Introduce domain_has_ioreq_server()
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Oleksandr <olekstysh@xxxxxxxxx>
- Date: Tue, 8 Dec 2020 17:33:42 +0200
- Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Ian Jackson <iwj@xxxxxxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Paul Durrant <paul@xxxxxxx>, Julien Grall <julien.grall@xxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 08 Dec 2020 15:33:53 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 08.12.20 17:11, Jan Beulich wrote:
Hi Jan
On 30.11.2020 11:31, Oleksandr Tyshchenko wrote:
--- a/xen/include/xen/ioreq.h
+++ b/xen/include/xen/ioreq.h
@@ -55,6 +55,20 @@ struct ioreq_server {
uint8_t bufioreq_handling;
};
+/*
+ * This should only be used when d == current->domain and it's not paused,
Is the "not paused" part really relevant here? Besides it being rare
that the current domain would be paused (if so, it's in the process
of having all its vCPU-s scheduled out), does this matter at all?do any extra
actionsdo any extra actions
No, it isn't relevant, I will drop it.
Apart from this the patch looks okay to me, but I'm not sure it
addresses Paul's concerns. Iirc he had suggested to switch back to
a list if doing a swipe over the entire array is too expensive in
this specific case.
We would like to avoid to do any extra actions in
leave_hypervisor_to_guest() if possible.
But not only there, the logic whether we check/set mapcache_invalidation
variable could be avoided if a domain doesn't use IOREQ server...
--
Regards,
Oleksandr Tyshchenko
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