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Mon, 06 May 2024 04:54:41 -0700 (PDT) Message-ID: Date: Mon, 6 May 2024 13:54:42 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 01/13] xen/common: add cache coloring common code Content-Language: en-US To: Carlo Nonato Cc: andrea.bastoni@minervasys.tech, Andrew Cooper , George Dunlap , Julien Grall , Stefano Stabellini , Marco Solieri , xen-devel@lists.xenproject.org References: <20240502165533.319988-1-carlo.nonato@minervasys.tech> <20240502165533.319988-2-carlo.nonato@minervasys.tech> 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: <20240502165533.319988-2-carlo.nonato@minervasys.tech> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 02.05.2024 18:55, Carlo Nonato wrote: > --- a/xen/common/Kconfig > +++ b/xen/common/Kconfig > @@ -71,6 +71,9 @@ config HAS_IOPORTS > config HAS_KEXEC > bool > > +config HAS_LLC_COLORING > + bool > + > config HAS_PIRQ > bool > > @@ -513,4 +516,23 @@ config TRACEBUFFER > to be collected at run time for debugging or performance analysis. > Memory and execution overhead when not active is minimal. > > +config LLC_COLORING > + bool "Last Level Cache (LLC) coloring" if EXPERT > + depends on HAS_LLC_COLORING > + depends on !NUMA > + > +config MAX_LLC_COLORS_ORDER May I ask that you consider dropping MAX_ from here (but keeping "maximum" in prompt and text), thus ... > --- /dev/null > +++ b/xen/common/llc-coloring.c > @@ -0,0 +1,111 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Last Level Cache (LLC) coloring common code > + * > + * Copyright (C) 2022 Xilinx Inc. > + */ > +#include > +#include > +#include > + > +#define NR_LLC_COLORS (1 << CONFIG_MAX_LLC_COLORS_ORDER) ... making this look less strange? To match up with e.g. max_nr_colors you may also want to use 1U here. > +void __init llc_coloring_init(void) > +{ > + unsigned int way_size; > + > + if ( llc_size && llc_nr_ways ) > + { > + llc_coloring_enabled = true; > + way_size = llc_size / llc_nr_ways; > + } > + else if ( !llc_coloring_enabled ) > + return; > + else > + { > + way_size = get_llc_way_size(); > + if ( !way_size ) > + panic("LLC probing failed and 'llc-size' or 'llc-nr-ways' missing\n"); Since you won't accept way_size == 0 here, how about it ending up zero in the initial if()'s body? Even more, don't you want to demand llc_size % llc_nr_ways == 0 there (thus, together with the enclosing condition, guaranteeing way_size != 0)? > + } > + > + /* > + * The maximum number of colors must be a power of 2 in order to correctly > + * map them to bits of an address. > + */ > + max_nr_colors = way_size >> PAGE_SHIFT; > + > + if ( max_nr_colors & (max_nr_colors - 1) ) > + panic("Number of LLC colors (%u) isn't a power of 2\n", max_nr_colors); > + > + if ( max_nr_colors > NR_LLC_COLORS ) > + { > + printk(XENLOG_WARNING > + "Number of LLC colors (%u) too big. Using configured max %u\n", > + max_nr_colors, NR_LLC_COLORS); > + max_nr_colors = NR_LLC_COLORS; > + } else if ( max_nr_colors < 2 ) > + panic("Number of LLC colors %u < 2\n", max_nr_colors); Ah, here's a check guaranteeing at least the first of the two things asked about above. Jan