Messages in this thread |  | | From | Rusty Russell <> | Subject | Re: [PATCH v5 10/10] module: Rework module_addr_{min,max} | Date | Tue, 14 Apr 2015 12:25:45 +0930 |
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Ingo Molnar <mingo@kernel.org> writes: > * Peter Zijlstra <peterz@infradead.org> wrote: > >> __module_address() does an initial bound check before doing the >> {list/tree} iteration to find the actual module. The bound variables >> are nowhere near the mod_tree cacheline, in fact they're nowhere >> near one another. >> >> module_addr_min lives in .data while module_addr_max lives in .bss >> (smarty pants GCC thinks the explicit 0 assignment is a mistake). >> >> Rectify this by moving the two variables into a structure together >> with the latch_tree_root to guarantee they all share the same >> cacheline and avoid hitting two extra cachelines for the lookup. >> >> While reworking the bounds code, move the bound update from >> allocation to insertion time, this avoids updating the bounds for a >> few error paths. > >> +static struct mod_tree_root { >> + struct latch_tree_root root; >> + unsigned long addr_min; >> + unsigned long addr_max; >> +} mod_tree __cacheline_aligned = { >> + .addr_min = -1UL, >> +}; >> + >> +#define module_addr_min mod_tree.addr_min >> +#define module_addr_max mod_tree.addr_max
Nice catch.
Does the min/max comparison still win us anything? (I'm guessing yes...)
In general, I'm happy with this series. Assume you want another go-round for Ingo's tweaks, then I'll take them for 4.2.
Thanks, Rusty.
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