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Davide Libenzi a écrit : > On Thu, 7 Jun 2007, Eric Dumazet wrote: > >> Davide, are you sure we want FIFO for non sequential allocations ? >> >> This tends to use all the fmap slots, and not very cache friendly >> if an app does a lot of [open(),...,close()] things. We already got a >> perf drop because of RCUification of file freeing (FIFO mode instead >> of LIFO given by kmalloc()/kfree()) >> >> If the idea behind this FIFO was security (ie not easy for an app to predict >> next glibc file handle), we/glibc might use yet another FD_SECUREMODE flag, >> wich ORed with O_NONSEQFD would ask to fdmap_newfd() to take the tail of >> fmap->slist, not head. > > Uli, would it be OK to rely only on base randomization and use a LIFO > instead? We have base randomization, plus LIFO does not mean strictly > sequential like legacy allocator, just more compatc and cache friendly. > I am afraid randomization wont really work if /sbin/init or /bin/bash for example uses one (or more) unseq fd : The 'random base' will be propagated at fork()/exec() time ? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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