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[37.24.206.209]) by smtp.gmail.com with ESMTPSA id he44-20020a1709073dac00b00a4323d1b18fsm804181ejc.34.2024.02.29.07.46.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Feb 2024 07:46:16 -0800 (PST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: acf19f64-d719-11ee-afd8-a90da7624cb6 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1709221576; x=1709826376; darn=lists.xenproject.org; h=content-transfer-encoding:in-reply-to:autocrypt:from:references:cc :to:content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=yvStt6RpT6Q49zFDLwqwelFVZVbqpoF3M0TQaFXVjFk=; b=aJgXDQGi3dkrOiIiocS9QnZwsB4s36KgC0e3XZ2jTpEJZRnfOwkSCm1OWmX/rmkQ3A 3GbGsVGN9A9Bi1IY0qhLd0qHaVh8143OMtBfLP3Z3iGcgi4MjlU3FtecQ+T3wsS1aLQ0 uWUmZhYfLISi92N1LgtmQZOLMelC0ZSJDQuwZ3NfbQIuNusGkJqkONg7bQmS7dye0uNz fI6kg0rWEHZc1OaRTQPQEOsadqu47SMjTuhiIc5ovMGObIo0DaKYMPgnWIvbeWpqbcR4 Fjq+13NCgDw73VqH5kInaZy+90oEDKRljG+t5/x5CjSMuquVLqTtu/Dv6Pti6joZMQGf 4TUw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1709221576; x=1709826376; h=content-transfer-encoding:in-reply-to:autocrypt:from:references:cc :to:content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=yvStt6RpT6Q49zFDLwqwelFVZVbqpoF3M0TQaFXVjFk=; b=q+jhEUHzkdQ312Ea+m46kxL8SwgAm/lLBifAahQPw8ZZlsrnFCf3hdPblITULzor3j cqjdrIAvA3DfuJUsxPbg/m+15Ygz8O5lkRTZsgCjxhdjuFhWf19QZopLhyOJ8QifGmA/ CZDKLi3wh7q7Qf5dpGwhh7DbNFra/ApiGox1aENLszTbtmjEV2xcE6am9feFj3Lq552Z zAn5h/D62duDkxogr6nxyaxEuyzgC+i/Cb1rH2O2nRfVYWMpz2wmjNOqFmVHgp16b0+U cm7ksEsrn5Za0gnirU/NybP9oVs7msDnlf6X6kY6zaCR00Y6BoaWAKinUwLA31BKHRco w+LA== X-Forwarded-Encrypted: i=1; AJvYcCWy32Qnq7Z/o2Oe0uli+4wP/7HiBP8K0YHSwiPbo7wsmWB1hw2uH9nh3hYdgzMoCgD+U90ffIz4EsaQ574zqUTe1pxPEXNNKW9TU9ECds0= X-Gm-Message-State: AOJu0YzCyxXNWtdvrd0qY3eovt7mfTjP0ezBaxjh/TppL3E4khq1o7Q9 noE3ZT0dsrsxtG5aA5sCNI2vVdxXfnZZFLM8TPMMxNg30ydTvYuXqzhfx3DBPQ== X-Google-Smtp-Source: AGHT+IHGX/jJLHhP0Gk2ekkO5WT9x5v3oH3WPAGQiTxxufBleiRuvX5yk4vx+Ae3mcMKcS3LCnhLcw== X-Received: by 2002:a17:906:46d9:b0:a44:4ee9:c560 with SMTP id k25-20020a17090646d900b00a444ee9c560mr1162166ejs.53.1709221576655; Thu, 29 Feb 2024 07:46:16 -0800 (PST) Message-ID: Date: Thu, 29 Feb 2024 16:46:15 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 12/12] xen/spinlock: support higher number of cpus Content-Language: en-US To: Juergen Gross Cc: Andrew Cooper , George Dunlap , Julien Grall , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org References: <20231212094725.22184-1-jgross@suse.com> <20231212094725.22184-13-jgross@suse.com> From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; 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 In-Reply-To: <20231212094725.22184-13-jgross@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 12.12.2023 10:47, Juergen Gross wrote: > Allow 16 bits per cpu number, which is the limit imposed by > spinlock_tickets_t. > > This will allow up to 65535 cpus, while increasing only the size of > recursive spinlocks in debug builds from 8 to 12 bytes. I think we want to be more conservative here, for the case of there being bugs: The CPU holding a lock may wrongly try to acquire it a 2nd time. That's the 65536th ticket then, wrapping the value. Therefore my suggestion would be to only (mention) go(ing) up to 32k. > Signed-off-by: Juergen Gross > --- > xen/common/spinlock.c | 1 + > xen/include/xen/spinlock.h | 18 +++++++++--------- > 2 files changed, 10 insertions(+), 9 deletions(-) Shouldn't this also bump the upper bound of the NR_CPUS range then in xen/arch/Kconfig? Jan