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[92.178.7.112]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-3a6e805d1e2sm4899093f8f.24.2025.06.25.08.46.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Jun 2025 08:46:38 -0700 (PDT) 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: 9511c2c2-51db-11f0-b894-0df219b8e170 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1750866398; x=1751471198; darn=lists.xenproject.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=0LojgLOCtW02dabTp+YFhUX08RNdTWTM2YGGvpuBMsg=; b=BNU8/zFsV7By3U2mWhPmAQdlMqmatRPuPxSASwrTFIyocS40vxCab3SS8+NPARkqkj 166L+Wn3hGXO6hHbsG04Rj8+WasOzr5XIEgNfol+6/POPU8ZgcCS9k0q0KKLmeHH2Yun puXF9XD9jeWbqtXpqSekxVBMbx5HYRjR+o+9U= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750866398; x=1751471198; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=0LojgLOCtW02dabTp+YFhUX08RNdTWTM2YGGvpuBMsg=; b=Pt3ltWytwZpXZLPpgiHxW04bdcfPK1PhUzogYprxayONppRYcBn2cLumZCDDP7iJCy E4LB+YhfXuv/ZI4JA4D/SZWv+zl3b3BYr2EEUye0feR4cBub1OSTFT6MdIMQuz+a9ZNN R5oyCTQCyIuNzWyWFRKc2dTCQODTuggq8A3aJAxi506MeIbgRoc01AI6KS2q9qSgCKIL qz576tYur1BdGLe8IJcvlUWkkXD/4Autd8BuUKRVeGbSPf4w3FK9gS8nUxEtmYIWMO6d B+buagr0E7fOMIJ62FpDQWaB/Wo9oIf9uPQjQnZsMpa+DLmEiwsdtxbQkwhKMK560tFN n4NQ== X-Forwarded-Encrypted: i=1; AJvYcCX8Ey9Tw+FgKrv+1l8wVKpoj7WrAVydNdT4OkKGj8OrsgrJgOqVn7SEzzRMPhxx4HABjGiDmuCqazU=@lists.xenproject.org X-Gm-Message-State: AOJu0YwL6jLWC2Y2vPglsIN4fkSUZ3cceACdeOnUWP3RgxJnDnTg6lsB kAXsVFRk0qdtte93I+3SRYzWfpQnMJjVfhWLsKVF4gymYfJF7HNdkdb1vLdJTd1VNdk= X-Gm-Gg: ASbGncszbrJrifQu7636Pd2/kRweJwnLx19JE6UQ97nXUVzECNz6mpZz7h/DayEs90f 6G5o86ERsFMJjXcAl2mQDsNMLM6b7llkhf4nnEwEtEkQE7gYJi9WlnTZ67KjiSrwKKYH02zRBjE w66d98dtg8M0VNqrY8pcGCZ2QnhbSYkSiU22hGItv5NUih0+xrAPjbZI847DvgNAGjltpGfu2Ht ZlzefqGgg8K8X6YsDlqN4gjR1NjSFDo0LgDjmQGYisHgp/HuAZ/6USixQPYWnTxXvXLi+nLeL40 RyElNCM0DrVfK12BvGcTOHy77BI0zkQoMV2F5bawxxgFeJeC7jozkYiX8eRmdBBVFCZ/VdRhP6l 2jzKgAtd7I1Euw4jaI8ndWF+Jw/byhw== X-Google-Smtp-Source: AGHT+IEaBje4n4tW3pprxvp31ACccblpyQwMt4pKIXwM5W+3kLDRM7hnt4DoqIiRPWBIazp78/ydjQ== X-Received: by 2002:a05:6000:2287:b0:3a5:27ba:47a8 with SMTP id ffacd0b85a97d-3a6ed65d23amr2936984f8f.52.1750866398437; Wed, 25 Jun 2025 08:46:38 -0700 (PDT) Date: Wed, 25 Jun 2025 17:46:37 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Jan Beulich Cc: Andrew Cooper , Anthony PERARD , Michal Orzel , Julien Grall , Stefano Stabellini , Roger Pau =?utf-8?B?TW9ubsOp?= , xen-devel@lists.xenproject.org Subject: Re: [PATCH v2 4/8] pdx: introduce command line compression toggle Message-ID: References: <20250620111130.29057-1-roger.pau@citrix.com> <20250620111130.29057-5-roger.pau@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Jun 24, 2025 at 03:40:16PM +0200, Jan Beulich wrote: > On 20.06.2025 13:11, Roger Pau Monne wrote: > > Introduce a command line option to allow disabling PDX compression. The > > disabling is done by turning pfn_pdx_add_region() into a no-op, so when > > attempting to initialize the selected compression algorithm the array of > > ranges to compress is empty. > > While neat, this also feels fragile. It's not obvious that for any > algorithm pfn_pdx_compression_setup() would leave compression disabled > when there are zero ranges. In principle, if it was written differently > for mask compression, there being no ranges could result in compression > simply squeezing out all of the address bits. Yet as long as we think > we're going to keep this in mind ... It seemed to me that nr_rages == 0 (so no ranges reported) should result in no compression, for example on x86 this means there's no SRAT. > > Signed-off-by: Roger Pau Monné > > Reviewed-by: Jan Beulich Thanks, Roger.