[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH] x86/APIC: Remove x2APIC pure cluster mode
- To: Roger Pau Monné <roger.pau@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Tue, 24 Sep 2024 18:21:47 +0200
- Autocrypt: addr=jbeulich@xxxxxxxx; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL
- Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx, Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>, Community Manager <community.manager@xxxxxxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Matthew Barnes <matthew.barnes@xxxxxxxxx>
- Delivery-date: Tue, 24 Sep 2024 16:21:56 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 24.09.2024 18:14, Roger Pau Monné wrote:
> On Tue, Sep 24, 2024 at 04:27:36PM +0100, Andrew Cooper wrote:
>> On 24/09/2024 4:10 pm, Roger Pau Monné wrote:
>>> On Mon, Sep 23, 2024 at 03:35:59PM +0100, Matthew Barnes wrote:
>>>> With the introduction of mixed x2APIC mode (using cluster addressing for
>>>> IPIs and physical for external interrupts) the use of pure cluster mode
>>>> doesn't have any benefit.
>>>>
>>>> Remove the mode itself, leaving only the code required for logical
>>>> addressing when sending IPIs.
>>>>
>>>> Implements: https://gitlab.com/xen-project/xen/-/issues/189
>>
>> We use the Resolves: tag for this. Can fix on commit.
>>
>>> There's at least one extra bit which I would also like to see removed,
>>> either in this patch, or as following patch.
>>>
>>> In struct arch_irq_desc we have 3 cpumasks: cpu_mask, old_cpu_mask and
>>> pending_mask. After dropping cluster mode for external interrupts,
>>> those fields could become integers AFACT, as now interrupts can only
>>> target a single CPU opposed to a logical CPU set.
>>
>> A separate patch for sure, but that sounds like a great improvement.
>
> Oh, there are quite some fields of struct genapic that are not needed
> anymore, since both implementations set it to the same function. It
> would be helpful to prune them.
Pruning where possible - yes. But "both" won't cover it, as we have 4
instances of the struct (not just the two x2apic ones).
Jan
|
