search for: fnv

I am trying to speed up some DB operations and perhaps have gone overboard with indexes. Does MySQL usually use only one index per query and simply match keys on the results of the indexed first part? For example: DELETE FROM tokens WHERE 6813946236211560448 <= fnv AND fnv < 6818449835838930944 AND updated_at<''2010-06-20 14:08:55'' AND occurrences=0; If I understand correctly from the output of: EXPLAIN SELECT * FROM tokens WHERE 6813946236211560448 <= fnv AND fnv < 6818449835838930944 AND updated_at<''2010-06-20 14:0...

In this patch series we use the newly introduced free callback on the completion function to dererence the OCaml NBD.Buffer. I will make the same kind of change for Python later in a separate series. The completion function is always called at the C level, even if the OCaml program didn't use the optional argument. That's because the free callback doesn't run otherwise. There is a

..."\n"; + pr " /* The C callback is always registered, even if there's no OCaml\n"; + pr " * callback. This is because we may need to unregister an\n"; + pr " * associated persistent buffer.\n"; + pr " */\n"; + pr " if (data->fnv == 0)\n"; + pr " CAMLreturnT (int, 0);\n"; List.iter ( function @@ -5079,19 +5080,19 @@ let print_ocaml_binding (name, { args; optargs; ret }) = List.iter ( function | OClosure { cbname } -> - pr " nbd_%s_callback %s_callback = {0};\n" c...

This is a combination of these two earlier series: https://www.redhat.com/archives/libguestfs/2019-August/msg00235.html https://www.redhat.com/archives/libguestfs/2019-August/msg00240.html plus changes to allow .callback = NULL / .free != NULL, and to reduce the complexity of freeing callbacks. Although it's rather long there's nothing complex here. We might consider squashing some

I'm working on a bug where LLVM takes over six minutes to compile a module. After some hand-editing, the module looks like this: class half { private: union uif { unsigned int i; float f; }; static const uif _toFloat[1 << 16]; }; const half::uif half::_toFloat[1 << 16] = { {0x00000000}, {0x33800000}, {0x34000000}, {0x34400000}, {0x34800000},

On Mon, Feb 08, 2010 at 10:31:23AM -0800, Chris Lattner wrote: > On Feb 7, 2010, at 1:03 PM, Gregory Petrosyan wrote: > > >On Sat, Feb 06, 2010 at 04:51:15PM -0800, Chandler Carruth wrote: > >>While I've not reviewed the patch in too much detail, it looks > >>promising. Can you run some end-to-end benchmarks to make sure that > >>cache pressure in the

..., which may contain character data, integers, or whatever - it's designed to do such a thorough job of mixing the bits that it really doesn't matter what data types you feed it. You are correct that for purely string data, you'd want to use a less expensive algorithm (I'm partial to FNV-1, which is as cheap as the Bernstein hash and is AFAIK more mathematically sound.) > // Add a possibly unaligned sequence of bytes. > void addImpl(const char *I, size_t Length) { > > This should probably be moved out of line to avoid code bloat. > OK > > Overall, the d...

..., which may contain character data, integers, or whatever - it's designed to do such a thorough job of mixing the bits that it really doesn't matter what data types you feed it. You are correct that for purely string data, you'd want to use a less expensive algorithm (I'm partial to FNV-1, which is as cheap as the Bernstein hash and is AFAIK more mathematically sound.) Ok, so what's the answer? :) We can do different things for ArrayRef<char> and StringRef. -Chris -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm...

...bit) faster. That's on long strings. It would be worth checking the startup overhead for typically short identifiers in programs. See later on in the README: "When used in a hash table the instruction cache will usually beat the CPU and throughput measured here. In my tests the smallest FNV1A beats the fastest crc32_hw1 with Perl 5 hash tables. Even if those worse hash functions will lead to more collisions, the overall speed advantage beats the slightly worse quality. See e.g. A Seven-Dimensional Analysis of Hashing Methods and its Implications on Query Processing for a concise overv...

...quot;; - pr "{\n"; - pr " CAMLparam0 ();\n"; - assert (List.length argnames <= 5); - pr " CAMLlocal%d (%s);\n" (List.length argnames) - (String.concat ", " argnames); - pr " CAMLlocal2 (fnv, rv);\n"; - pr " value args[%d];\n" (List.length argnames); - pr "\n"; + pr "/* Wrapper for %s callback of %s. */\n" cbname name; + pr "static int\n"; + pr "%s_%s_wrapper_locked " name cbname; + C.pr...

...ecorded). > > For Python and OCaml bindings, raising any kind of exception from the > callback is equivalent to returning -1 from the C callback. > --- > @@ -3957,24 +3963,34 @@ let print_ocaml_binding (name, { args; ret }) = > > pr " rv = caml_callbackN_exn (fnv, %d, args);\n" > (List.length argnames); > - pr " if (Is_exception_result (rv))\n"; > + pr " if (Is_exception_result (rv)) {\n"; > + pr " /* XXX This is not really an error as callbacks can return\n"; > + pr &...

Patches 1-4 are basically uncontroversial, straightforward refactoring and IMHO we should just push them. Possibly 1-3 should be squashed together, but I posted them separately so they are easier to review. Patches 5 and 6 together implement OClosure. Patch 5 adds the feature and is simple to understand. Patch 6 changes the Closure completion callbacks into OClosure, but because it doesn't

...44][ T5040] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 > [ 463.718848][ T5040] Mem abort info: > [ 463.718849][ T5040] ESR = 0x96000044 > [ 463.718852][ T5040] EC = 0x25: DABT (current EL), IL = 32 bits > [ 463.718853][ T5040] SET = 0, FnV = 0 > [ 463.718854][ T5040] EA = 0, S1PTW = 0 > [ 463.718855][ T5040] Data abort info: > [ 463.718856][ T5040] ISV = 0, ISS = 0x00000044 > [ 463.718857][ T5040] CM = 0, WnR = 1 > [ 463.718859][ T5040] user pgtable: 4k pages, 48-bit VAs, pgdp=0000008f6f6e9000 > [ 463.71...

...44][ T5040] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 > [ 463.718848][ T5040] Mem abort info: > [ 463.718849][ T5040] ESR = 0x96000044 > [ 463.718852][ T5040] EC = 0x25: DABT (current EL), IL = 32 bits > [ 463.718853][ T5040] SET = 0, FnV = 0 > [ 463.718854][ T5040] EA = 0, S1PTW = 0 > [ 463.718855][ T5040] Data abort info: > [ 463.718856][ T5040] ISV = 0, ISS = 0x00000044 > [ 463.718857][ T5040] CM = 0, WnR = 1 > [ 463.718859][ T5040] user pgtable: 4k pages, 48-bit VAs, pgdp=0000008f6f6e9000 > [ 463.71...

...ystemd-udevd. > > [ 12.050625] Unable to handle kernel NULL pointer dereference at virtual > address 00000058 > [ 12.050627] Mem abort info: > [ 12.050628] ESR = 0x96000004 > [ 12.050630] Exception class = DABT (current EL), IL = 32 bits > [ 12.050631] SET = 0, FnV = 0 > [ 12.050632] EA = 0, S1PTW = 0 > [ 12.050633] Data abort info: > [ 12.050634] ISV = 0, ISS = 0x00000004 > [ 12.050635] CM = 0, WnR = 0 > [ 12.050637] user pgtable: 4k pages, 48-bit VAs, pgd = 00000000af2ac1b1 > [ 12.050639] [0000000000000058] *pgd=000000000...

...a crash when nouveau is loaded by systemd-udevd. [ 12.050625] Unable to handle kernel NULL pointer dereference at virtual address 00000058 [ 12.050627] Mem abort info: [ 12.050628] ESR = 0x96000004 [ 12.050630] Exception class = DABT (current EL), IL = 32 bits [ 12.050631] SET = 0, FnV = 0 [ 12.050632] EA = 0, S1PTW = 0 [ 12.050633] Data abort info: [ 12.050634] ISV = 0, ISS = 0x00000004 [ 12.050635] CM = 0, WnR = 0 [ 12.050637] user pgtable: 4k pages, 48-bit VAs, pgd = 00000000af2ac1b1 [ 12.050639] [0000000000000058] *pgd=0000000000000000 [ 12.050643] Interna...

..."static void\n"; + pr "static int\n"; pr "%s_%s_wrapper_locked " name cb_name; print_c_arg_list args; pr "\n"; @@ -3957,24 +3963,34 @@ let print_ocaml_binding (name, { args; ret }) = pr " rv = caml_callbackN_exn (fnv, %d, args);\n" (List.length argnames); - pr " if (Is_exception_result (rv))\n"; + pr " if (Is_exception_result (rv)) {\n"; + pr " /* XXX This is not really an error as callbacks can return\n"; + pr " * an error indi...

v1 was here: https://www.redhat.com/archives/libguestfs/2019-July/thread.html#00231 The changes address everything that Eric picked up in his review of the first two patches. I have also added two more patches (4 and 5) which respectively fix docs and change int status -> unsigned status, as discussed. Passes make, check, check-valgrind. Rich.

This implements most of what I wrote here: https://www.redhat.com/archives/libguestfs/2019-July/msg00213.html

...uot; n len; + pr " memcpy (String_val (%sv), %s, %s);\n" n n len | String n -> pr " %sv = caml_copy_string (%s);\n" n n | UInt64 n -> @@ -3937,7 +3974,7 @@ let print_ocaml_binding (name, { args; ret }) = pr " fnv = *_%s->cb;\n" n; pr " %sv = *_%s->data;\n" n n (* The following not yet implemented for callbacks XXX *) - | ArrayAndLen _ | Bool _ | BytesIn _ | BytesOut _ + | ArrayAndLen _ | Bool _ | BytesOut _ | BytesPersistIn _ | BytesPers...